Depending on how, in hindsight, you rate the Portland Timbers' 5-2 win over LA in October, the Timbers' 3-1 win over Dallas in the first leg of the Western Conference Final last Sunday might have been the club's most impressive triumph of the year.

It also might have been the most important, because, on the penultimate day of the 2015 season, it puts the Timbers on the brink of reaching MLS Cup. Dallas, the West's #1 seed, has an absolute mountain to climb in the second leg of the tie on Sunday in Frisco (Sunday at 5:00 PM, TV on ESPN). Instead of the suffocating heat, freezing rain is expected for the match as the home team tries to overturn a two-goal deficit.

The Timbers will get Diego Valeri and Rodney Wallace back for the match, and face something of a selection dilemma as Caleb Porter weighs his approach. If the Timbers score, Dallas needs four goals to advance—but an early Dallas goal will set the Timbers up with a razor-thin margin for error. With the Western Conference championship on the line, this is, quite simply, the biggest game in the history of the Portland Timbers.

The History

Last Sunday's first leg went about as well as the Timbers could have hoped for. They scored early, they scored late, they mostly neutralized Dallas' playmakers, and they won a commanding series lead. If that all wasn't enough, Dairon Asprilla's goal was one of the three best in the team's MLS history.

Portland's experience showed last week. The Timbers victimized Dallas on set pieces, with goals coming from Liam Ridgewell and Nat Borchers at the beginning and end of each half. Dallas mostly kept its composure—though Diego Chara was the victim of several stomps—and put together some nice stretches, but Portland always looked in control.

The Timbers' current run—six wins out of seven, with three of those victories coming in the playoffs—is the best in club history. Dallas will hang its hopes on its terrific form at Toyota Stadium this year. Their 13 regular season home wins were the most in MLS, and one of those victories was a 4-1 beat-down of the Timbers in July.

Dallas also had its back against the wall at home in the last round and ended up beating Seattle on penalties in the second-most thrilling game in this postseason, but overturning a 2-1 deficit against the Sounders is much different than a 3-1 deficit against these Timbers.

The Tactics

With everyone expecting a farewell start from Will Johnson last Sunday in lieu of Valeri, Johnson got a farewell minute at the end of the game while good old Jack Jewsbury went 90 terrific minutes in the middle of the park in Porter's 4-2-3-1.

With Jewsbury shielding the already highly-competent defense just behind Diego Chara, Portland's front four—including wingers Lucas Melano and Asprilla—had license to be aggressive and get forward at will. The setup got the most out of the Timbers' available personnel last Sunday, but with Valeri and Wallace coming back, it all might change again.

Portland can go back to what has been its first-choice alignment—the inverted 4-3-3 with Chara playing the single pivot along with Darlington Nagbe and Diego Valeri in midfield and Asprilla and Wallace wide—but it's a more attacking formation than the 4-2-3-1 with Jewsbury. Chances are that Porter will not eschew attacking, considering how huge the task for Dallas would become if the Timbers got an away goal, so the 4-3-3 looks more likely.

But it was Jewsbury who helped plenty in leg one on Mauro Diaz, Dallas' playmaker and one of the five best players in the league, and if he doesn't start, Nagbe is going to have to play plenty of defense to help Chara on Diaz. Portland needs another strong game from its fullbacks, with Alvas Powell looking vulnerable at times last Sunday. One figures that Adam Kwarasey will have much more to do in this game than he did in Portland, while young Dallas 'keeper Jesse Gonzalez was shaky on the other end of the field.

Liam Ridgewell might be a big miss for Portland, as he's struggling with the calf problem that saw him forced out of the first leg midway through the second half. Should Ridgewell be unable to go, Norberto Paparatto will start.

In the second leg against Seattle, Dallas dominated but didn't break through until after the 80th minute. Knowing they need at least two goals to advance, Oscar Pareja's team will come out with its hair on fire — much like Vancouver did at BC Place. But after weathering something of an early storm from the Whitecaps, the Timbers advanced easily. They'll be looking to do the same in Texas.

The Lineups

FC Dallas

44 - Gonzalez
27 - Watson
17 - Loyd
24 - Hedges (C)
12 - Hollingshead
23 - Acosta
8 - Ulloa
21 - Barrios
10 - Diaz
11 - Castillo
9 - Texeira

Portland Timbers

12 - Kwarasey
2 - Powell
23 - Paparatto
7 - Borchers (C)
19 - Villafaña
21 - Chara
6 - Nagbe
8 - Valeri
22 - Wallace
11 - Asprilla
9 - Adi

The Pick

Dallas will score first and make things interesting—but the Timbers defense will stand strong, the attack will nab an away goal, and, in front of over 250 members of the Timbers Army and Lone Star Brigade, Portland will advance to MLS Cup.