Caleb Porter made a splash in his first season in Major League Soccer back in 2013 when he led the Portland Timbers to first place in the Western Conference standings.

Four years later, the Timbers have finally returned to the top of the West.

Portland (15-11-8, 53 points) beat the Vancouver Whitecaps (15-12-7, 52 points) 2-1 in its regular season finale in front of 21,144 fans at Providence Park Sunday to move into first place in the Western Conference, win the Cascadia Cup and secure a first-round bye in the MLS Cup Playoffs.

"For us to be, after 34 games, nine and a half months, at the top of the West says everything about the group I have in that locker room," Porter said. "We earned it. We deserved it."

The Timbers will face the lowest-seeded winner of a midweek knockout game in a two-leg conference semifinal series beginning either next Sunday or on Tuesday, Oct. 31. This will be Portland's first appearance in the playoffs since the club won MLS Cup in 2015.

Before Sunday, Vancouver had a history of crushing Portland's playoff hopes.

The Whitecaps knocked the Timbers out of playoff contention in 2014 as they claimed the final spot in the postseason for themselves. Vancouver then beat the Timbers on the final day of the regular season in 2016 to end Portland's season.

But the Timbers flipped the script Sunday afternoon.

Vancouver entered Sunday's match in first place in the Western Conference standings, but former Whitecaps forward Darren Mattocks scored the game-winning goal for Portland in the 48th minute as the Timbers took over the top spot in the West.

Mattocks was starting his eighth-straight game in place of injured Timbers striker Fanendo Adi, who remains sidelined with a lingering hamstring injury.

"For me, it's about whatever it takes to help the team win, offensively and defensively," Mattocks said. "It doesn't always come off, but I'm always out there giving my best. Fortunate for me to get a goal tonight. It was really massive."

Portland had to overcome an early one-goal deficit to earn the victory Sunday.

The Timbers had a slow start to the match and conceded a slew of set pieces in dangerous spots early in the first half. The Whitecaps finally made them pay for it.

Vancouver center back Kendall Waston headed in a free kick from Yordy Reyna in the 29th minute to give the Whitecaps a 1-0 lead on the road.

"He made a good play there, credit to him," Porter said. "What I like about my group is they gave us their best punch and we didn't flinch. We came right back, leveled it, and at the start of the second half, you saw how badly we wanted to win this game."

The concession was a wake-up call for Portland.

The Timbers responded with the equalizer three minutes later as Liam Ridgewell scored on a rebound after Darlington Nagbe saw his shot blocked by Stefan Marinovic following a corner kick.

"It was big scoring and equalizing before we went in before halftime," Ridgewell said. "We felt like we played well in the first half and deserved a goal."

Portland continued to pressure the Whitecaps for the remainder of the first half, outshooting Vancouver 10-2 in the first 45 minutes. The Timbers didn't let up in the second half.

Timbers midfielder Sebastian Blanco found defender Vytas driving toward goal in the 48th minute. Marinovic tried to beat Vytas to the ball, but Vytas managed to slot a pass off to Mattocks, who sent his game-winning shot through two defenders and into the net.

Portland, which entered the match with a 0.75 goals against average and four shutouts in its last eight games, kept the Whitecaps off the board in the second half to secure the 2-1 win.

"It's obviously been a very long, hard season for everybody," Ridgewell said. "To get the number one seed is obviously a massive thing. It gives us a break during the week. It gives us confidence going into that next game and going into the playoffs to make something happen."

After the final whistle blew Sunday, Porter quickly shifted his focus to the postseason and preparing his club to make a serious run in the MLS Cup Playoffs.

"I think in my five years, we're playing as good of football as any team I've had here," Porter said.

-- Jamie Goldberg | jgoldberg@oregonian.com

503-853-3761 | @jamiebgoldberg