Along with the still-streaking Houston Rockets, the rest of the Power Rankings' top four remain unchanged. The real action, though, starts at No. 5, where the surging Portland Trail Blazers have won six straight to leapfrog the Cleveland Cavaliers.

Portland isn't the only West contender vaulting up our list. Anthony Davis and the New Orleans Pelicans, winners of eight straight, have gone from first-round fodder to challenging for home court in a matter of weeks.

Every week throughout the regular season, our panel (ESPN's Kevin Arnovitz, Amin Elhassan and Ramona Shelburne, The Undefeated's Marc J. Spears and FiveThirtyEight's Chris Herring) will rank the league's 30 teams from top to bottom, with research notes on each team provided by ESPN Stats & Information.

Week: 20 | 19 | 18 | 17 | 16 | 15 | 14 | 13

12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1

1. Houston Rockets

2017-18 record: 49-13

PREV. RANK LAST WEEK THIS WEEK 1 3-0 @OKC, @MIL, @TOR, @DAL

Houston can't stop winning, extending its streak to 15 games on Saturday night, tying the second-longest in franchise history; the Rockets won 22 straight games during the 2007-08 season. Houston has found a lot of success in isolation, not only during the streak, but the entire season: According to Second Spectrum, the Rockets are averaging 1.11 points per direct iso, which leads the NBA. -- Matt Williams

2. Golden State Warriors

2017-18 record: 49-14

PREV. RANK LAST WEEK THIS WEEK 2 3-0 BKN, SA, @POR, @MIN

The Warriors are 5-0 since the All-Star break and play again on Tuesday against the Nets. With a win, it would mark the Warriors' fifth straight season with at least 50 wins. Prior to this stretch, Golden State had only four 50-win seasons in franchise history (1993-94, 1991-92,1975-76 and 1971-72). -- Matt Williams

3. Toronto Raptors

2017-18 record: 45-17

PREV. RANK LAST WEEK THIS WEEK 3 4-0 ATL, @DET, HOU, @NY

The Raptors haven't lost consecutive games since Jan. 15 and haven't suffered a double-digit loss since Dec. 27 against the Thunder. Toronto ranks among the top five in offensive efficiency (fifth), defensive efficiency (second) and net efficiency (third). Though they're only two games ahead of Boston for the East's top seed, this team might boast the most viable Finals hopes in franchise history. -- James Jackson

4. Boston Celtics

2017-18 record: 44-20

PREV. RANK LAST WEEK THIS WEEK 4 2-1 @CHI, @MIN, IND

Boston lost a tough one in Houston, with Al Horford providing his worst plus-minus (minus-22) in 127 games as a Celtic. That said, the Celtics still sit only two games behind the Raptors for the East's top seed with two matchups remaining against Toronto. -- James Jackson

5. Portland Trail Blazers

2017-18 record: 37-26

PREV. RANK LAST WEEK THIS WEEK 7 3-0 @LAL, NY, GS

Look out for the Trail Blazers, who have won their past six games. The biggest reason? Their defense: Portland has allowed 98.1 points per 100 possessions during the winning streak, best in the NBA over that span. -- Matt Williams

6. Cleveland Cavaliers

2017-18 record: 36-26

PREV. RANK LAST WEEK THIS WEEK 5 1-2 DET, @DEN, @LAC, @LAL

The Cavaliers are 2-4 since the All-Star break and are allowing 109.7 points per 100 possessions over that span (they gave up 109.8 points per 100 possessions before the break). But a bigger head-scratcher could be the lineups the Cavaliers use. The grouping of LeBron James along with new arrivals Rodney Hood, Jordan Clarkson, Larry Nance Jr. and George Hill has recorded a point differential of plus-15 since the break but has played only 12 minutes together. -- Matt Williams

7. New Orleans Pelicans

2017-18 record: 36-26

PREV. RANK LAST WEEK THIS WEEK 16 3-0 @LAC, @SAC, WAS, UTAH

The Pelicans have won eight straight games, their longest winning streak since January 2011, when Chris Paul led the then-Hornets to a team-record 10 straight. To no one's surprise, Anthony Davis has been at the heart of New Orleans' surge to fourth in the West. In the past 40 seasons, only The Brow, Shaquille O'Neal, Moses Malone and Karl Malone have averaged 35 points and 10 rebounds over an eight-game win streak, according to the Elias Sports Bureau. -- James Jackson

8. San Antonio Spurs

2017-18 record: 36-27

PREV. RANK LAST WEEK THIS WEEK 6 0-2 MEM, @GS, @OKC

San Antonio has hit a rough patch as of late, going 2-8 in its past 10 games. According to the Elias Sports Bureau, that is the worst 10-game stretch for the Spurs since they went 2-8 in the final 10 games of the 1996-97 season. The Spurs have also lost two straight home games after leading by 15 or more points in the second half, something they hadn't done in 325 straight home games under the same scenario. -- Doug Clawson

9. Oklahoma City Thunder

2017-18 record: 37-28

PREV. RANK LAST WEEK THIS WEEK 13 3-1 HOU, PHX, SA

If Russell Westbrook posts a triple-double in each of the Thunder's three games this week, he would become the fourth player in NBA history with 100 career triple-doubles, joining Oscar Robertson (181), Magic Johnson (138) and Jason Kidd (107). -- Matt Williams

10. Philadelphia 76ers

2017-18 record: 34-28

PREV. RANK LAST WEEK THIS WEEK 12 2-2 @CHA, @MIA, @BKN

Philadelphia has won 11 straight home games, last losing as the designated "home" team in London on Jan. 11 against the Celtics. That is the longest home winning streak for the 76ers since a 24-game streak in 1982-83; Philly won the NBA title that season. -- Matt Williams

11. Washington Wizards

2017-18 record: 36-28

PREV. RANK LAST WEEK THIS WEEK 8 1-3 MIA, @NO, @MIA

Despite missing John Wall, the Wizards have impressed, going 10-6 in his absence. Bradley Beal is coming off his first career 10-assist game and is averaging 6.9 dimes in 16 games without Wall. He could use his fellow All-Star back, though, as Washington has lost three straight home games for the first time since November and play four of their next seven on the road, all against teams over .500. -- James Jackson

12. Indiana Pacers

2017-18 record: 36-27

PREV. RANK LAST WEEK THIS WEEK 9 2-2 MIL, UTAH, ATL, @BOS

Victor Oladipo's 11th 30-point game on Sunday night gave the Pacers a 2-2 record on a four-game road trip last week. With a 15-16 road record for the season, they will be happy to head back to Indiana for three consecutive games at Bankers Life Fieldhouse, starting Monday. -- Sopan Shah

13. Denver Nuggets

2017-18 record: 35-28

PREV. RANK LAST WEEK THIS WEEK 14 2-1 @DAL, CLE, LAL, SAC

Nikola Jokic had an odd week. In the Nuggets' two losses, he averaged 19.5 points, 10.0 boards and 6.0 assists. In their two wins, Jokic didn't reach double-digits in points or rebounds, shooting 39 percent. With just two games separating them from 10th-place Utah, the Nuggets will need to smooth things out to earn their first playoff berth since 2012-13. -- James Jackson

14. Utah Jazz

2017-18 record: 33-30

PREV. RANK LAST WEEK THIS WEEK 15 2-1 ORL, @IND, @MEM, @NO

The Jazz have won 14 of their past 16 games, with the only losses coming against the red-hot Trail Blazers and Rockets. And more wins could be on the way: Six of Utah's next nine games are against teams at least 20 games below .500. -- Matt Williams

15. Minnesota Timberwolves

2017-18 record: 38-28

PREV. RANK LAST WEEK THIS WEEK 11 1-2 BOS, GS

The Timberwolves have a tough stretch ahead -- facing the Celtics, Warriors, Spurs and Rockets in four of their next five games. BPI favors the Wolves in only one of those five games: Thursday's against the Celtics, which is in Minnesota. -- Sarah Langs

16. Milwaukee Bucks

2017-18 record: 34-29

PREV. RANK LAST WEEK THIS WEEK 10 1-3 @IND, HOU, NY

Against the 76ers, Milwaukee snapped a season-long four-game losing streak by becoming the second team in the past decade to overcome multiple 15-point deficits in a victory, according to the Elias Sports Bureau. With the Bucks 2.5 games out of the third seed in the East, Giannis Antetokounmpo will need more support beyond Eric Bledsoe (20.3 points per game, 51 percent shooting since Feb. 4) for the team to make some playoff noise. Milwaukee's bench is last in points per game this season (25.3). -- James Jackson

17. LA Clippers

2017-18 record: 34-28

PREV. RANK LAST WEEK THIS WEEK 17 3-1 NO, CLE, ORL

Since their first game after trading Blake Griffin (Jan. 30), the Clips are sixth in offensive efficiency and seventh in net efficiency (plus-3.8). Lou Williams has deservedly received credit for carrying LA's offense, but the newly acquired Tobias Harris has also maintained his career year from deep (41 percent on 3-pointers) since moving West 12 games ago, providing welcomed frontcourt spacing for DeAndre Jordan to dominate inside. -- James Jackson

18. Los Angeles Lakers

2017-18 record: 28-34

PREV. RANK LAST WEEK THIS WEEK 21 3-0 POR, ORL, @DEN, CLE

After missing 15 games with a left knee injury, Lonzo Ball is 14-for-22 on 3-pointers (64 percent) in four games. Ball was shooting 30 percent on 3s in his first 36 games this season. -- Doug Clawson

19. Miami Heat

2017-18 record: 33-30

PREV. RANK LAST WEEK THIS WEEK 19 2-1 PHX, @WAS, PHI, WAS

The Heat are holding onto the East's eighth seed, but not very convincingly. Since their season-best seven-game winning streak, Miami is 8-13 and ranks 24th in offensive efficiency (103.5 points per 100 possessions). Although Dwyane Wade's late-game heroics were fun to watch last week, All-Star Goran Dragic's plus-minus is better with Wade off the court (plus-44) than on (plus-6) in the eight games since Wade's return. -- James Jackson

20. Charlotte Hornets

2017-18 record: 28-36

PREV. RANK LAST WEEK THIS WEEK 18 1-3 PHI, BKN, PHX

The Hornets are stuck in NBA purgatory: too inconsistent for a compelling playoff seed or lottery pick. Charlotte's 15 wins since Jan. 1 are tied for fourth in the East, but they're still 5.5 games out of the eighth seed. Fortunately, the Hornets have the opportunity to continue making ground, as they have the NBA's third-easiest remaining schedule, according to ESPN's BPI. -- James Jackson

21. Detroit Pistons

2017-18 record: 29-34

PREV. RANK LAST WEEK THIS WEEK 20 1-3 @CLE, TOR, CHI

The Blake Griffin era in Detroit started off 4-0, but it has gone downhill since. The Pistons are 2-8 in their past 10 games, and Griffin is struggling from the field, shooting 39 percent from the floor and 27 percent on 3-pointers. -- Matt Williams

22. New York Knicks

2017-18 record: 24-40

PREV. RANK LAST WEEK THIS WEEK 22 0-3 @POR, @MIL, TOR

The news continues to be bad for the Knicks without Kristaps Porzingis. With their loss on Sunday, the Knicks fell to 2-14 without Porzingis this season (they were 22-26 with him). It'll be another season without a playoff appearance for the Knicks. The Knicks have won just one playoff series since 2000-01. In that span, almost every other team in the NBA (the Pelicans are the one exception) has won multiple playoff series. -- Sarah Langs

23. Chicago Bulls

2017-18 record: 21-41

PREV. RANK LAST WEEK THIS WEEK 23 1-2 BOS, MEM, @DET, @ATL

The Bulls overcame an 11-point fourth-quarter deficit on Friday to defeat the Mavericks. Entering the game, Chicago was 0-31 this season when trailing by at least 10 points in the fourth. -- Matt Williams

24. Orlando Magic

2017-18 record: 20-43

PREV. RANK LAST WEEK THIS WEEK 26 2-2 @UTAH, @LAL, @SAC, @LAC

The Magic offense has been on fire of late, recording its 12th consecutive 100-point game on Saturday against the Grizzlies. That's Orlando's longest streak since February 1995. The leading scorer on the team during that streak was Shaquille O'Neal. -- James Jackson

25. Brooklyn Nets

2017-18 record: 20-44

PREV. RANK LAST WEEK THIS WEEK 24 1-3 @GS, @CHA, PHI

Jarrett Allen has gotten in a nice groove of late, averaging 12.6 points per game on 67 percent shooting over his past 17 games. Prior to this stretch, he averaged 6.0 points per game and scored in double figures in nine of 38 games. -- Jose De Leon

26. Sacramento Kings

2017-18 record: 20-44

PREV. RANK LAST WEEK THIS WEEK 25 2-3 NO, ORL, @DEN

Few things have gone right for the Kings. Fortunately, they have an interesting backcourt in lottery pick De'Aaron Fox (4.3 assists per game) and Bogdan Bogdanovic, who is shooting 44 percent from deep since Jan. 1 and recently joined Jason Williams as the only Kings rookies to make 100 3-pointers in a season. -- James Jackson

27. Dallas Mavericks

2017-18 record: 19-45

PREV. RANK LAST WEEK THIS WEEK 28 1-3 DEN, MEM, HOU

On Friday, the Mavericks led the Bulls by 11 points with 10 minutes to play but were outscored 28-9 the rest of the way in a loss. It was their league-leading fifth loss of the season when leading by double figures with 10 minutes to play in the fourth quarter. -- Jose De Leon

28. Atlanta Hawks

2017-18 record: 20-44

PREV. RANK LAST WEEK THIS WEEK 27 2-2 @TOR, @IND, CHI

Sunday's win over the Suns was the third game the Hawks have won this season in which they hit a game winner with less than 10 seconds left. Kent Bazemore, a DNP-Rest on Sunday, hit the other two before Taurean Prince drained the off-balance 3 Sunday. If the Hawks had lost all three of those games, they would have the NBA's worst record. Instead, they now have the fifth-worst record and a 13.4 percent chance at the No. 1 overall draft pick, according to BPI. -- Micah Adams

29. Memphis Grizzlies

2017-18 record: 18-44

PREV. RANK LAST WEEK THIS WEEK 29 0-4 @SA, @CHI, UTAH, @DAL

After losing 13 straight games and going winless the entire month of February, the Grizzlies have the worst winning percentage in the NBA. The losing streak is their longest within a single season since 2002-03, when they lost their first 13 games. -- Matt Williams

30. Phoenix Suns

2017-18 record: 19-46

PREV. RANK LAST WEEK THIS WEEK 30 1-3 @MIA, @OKC, @CHA

One bright spot for the Suns has been the play of Devin Booker, who recorded his 40th career 30-point game on Friday against the Thunder. According to the Elias Sports Bureau, Booker is the fourth player in NBA history with at least 40 30-point games prior to turning 22, joining LeBron James (100), Kevin Durant (75) and Carmelo Anthony (45). -- Matt Williams