The way his roster has fluctuated this season with injuries to key backups like Tyler Johnson and Josh McRoberts, Heat coach Erik Spoelstra has often looked like a mad scientist in the fourth quarter, trying to find the right combinations in his lineup to create a winning chemistry.

For most of the season, he's stayed away from using Hassan Whiteside in the final period and opted to go small and fast, moving his most prolific weapon in Chris Bosh (now plus-58 for the season in the 4th quarter, 20th NBA, tops on Heat) to center and allowing the pieces around him (Justise Winslow, Gerald Green key among them) to help him as he attacks the basket early in the final period.

Usually around the 6 minute mark, Spoelstra brings in his closer, Dwyane Wade (plus 31 in clutch situations, 14th in NBA) to bring the Heat home like he did again on Saturday night against the Magic.

The guys shooting the basketball in key situations -- Bosh, Wade and now Green (plus 32 in clutch situations, 13th in NBA) -- doesn't figure to change. What has in the past week is Whiteside's sudden heavy workload in the fourth.

In three of the Heat's last four games, Whiteside, ninth on the team through Miami's first 25 games in fourth quarter minutes, has played 11 minutes or more in the final period. Suddenly, the 7-foot center Spoelstra hasn't opted to use with the game on the line, is not only out there, but he's producing.

Saturday night against the Magic, he and Green played all 12 minutes in the fourth quarter and were part of a relatively new lineup Spoelstra has now gone with twice in the last week to open the fourth quarter. The others on it: Bosh, Winslow and third-string point guard Beno Udrih, who has been pressed into more duty with Johnson out.

Both times that group has been out on the floor together to open the fourth quarter -- vs. the Magic and last Sunday against the Portland Trail Blazers -- they've turned a deficit into a lead before Wade or point guard Goran Dragic have returned to replace Udrih and Bosh. Of the Heat's 93 different fourth quarter, five-man lineups Spoelstra has used that Bosh-Whiteside-Udrih-Winslow-Green lineup is now the fourth-most successful unit at plus-12.

Sure, it's only a two-game sample size. But when you are desperate to find winning combinations in the NBA having lightning strike twice with something is often good enough for a coach to continue to come back with.

All of this of course comes back to Whiteside, who is doing more of late in terms of playing team basketball (setting screens, stepping out on shooters and rushing back to defend the paint and rebound) to warrant the usage by Spoelstra.

Over the last four games, Whiteside has played 39 minutes in the fourth quarter (second-most on the team) and is six of eight on field goal attempts, 4 of 4 from the free throw line with 18 points, 14 rebounds, 1 turnover and a plus-nine overall.

Through the Heat's first 25 games, Whiteside sat out seven times in the fourth quarter, was 10 of 22 from the free throw line, and was a minus-12 overall.

"He was playing spectacular basketball," Bosh said of Whiteside after Saturday's win. "He was the backside of that defense. He's the anchor. Yeah, [Nikola] Vucevic was making it tough on him. He was inside and outside and was just playing his game. But he eventually caught a rhythm for him.

"We couldn't have won this game without him. Sometimes it's going to be like for him and really for all of us. Just because you don't show up in the stat sheet doesn't mean you weren't an important piece for wins. We all have to remember that and if its not our night we just keep doing what we're doing, keep playing defense, keep getting second chances and live with it. He can't lose sight of that. As long as we get the win, that's what's most important."

It's going to be interesting to see how Spoelstra tinkers with his fourth quarter lineup on Monday against the Nets when Johnson (left shoulder impingement) said he's hoping to return after missing eight of the last nine games. Will he let Udrih, an unselfish, steady hand at the point, remain in his early fourth quarter role or put Johnson, his backup point guard, into his usual spot? We'll have to wait and see.