The Portland Timbers and Seattle Sounders, two of the fiercest rivals in MLS, have played many memorable regular season games. However, the two sides haven’t met in the playoffs since 2013. That Conference Semifinal series resulted in a 5-3 aggregate win for the top-seeded Timbers.

The roles are reversed this time around with the second seeded Sounders holding home field advantage over the Timbers, who needed to get by FC Dallas in the knockout round to reach this point.

Here’s a deeper look into the next chapter of this storied rivalry.

Season Series

These two sides met three times in the regular season and the road team won two of the three games. Portland won the opener at Providence Park thanks to an 86th-minute goal from Sebastian Blanco. They also traveled to Seattle to take the second match with a 3-2 win at CenturyLink Field. The Sounders experienced their annual midseason renaissance after that match, however, and took the third game in Oregon 1-0 on a Julio Cascante own goal.

Players to Watch

Portland Timbers: Diego Valeri

Portland will only go as far as Valeri can take them and he proved that in the knockout round against FC Dallas when he scored both of their goals in the 2-1 win. He will need another big game or two if he wants to see his team advance to the Conference Finals for the third time in their history.

Seattle Sounders: Raul Ruidiaz

The Peruvian arrived in the middle of the season and proceeded to kickstart Seattle’s midsummer surge. He’s only played in 13 games for the Sounders and he’s scored ten goals while becoming of of their most efficient passers. He’s a real offensive weapon in every sense of the term and, as we’re about to discuss, his ability to go against a short handed Timbers backline is certainly key for Seattle.

Matchup to Watch

Portland Timbers Defense vs. Seattle Sounders Attack

It cannot be stressed enough how important defending is for the Timbers in this series and the first leg in particular. Seattle has plenty of big name players up front and with the Timbers shorthanded at the back they will have quite the challenge in front of them,

Portland’s defending will play a big role in how they work up front as well. If the Sounders control possession, look for the Timbers to win the ball back in their own half and proceed to use fullbacks Jorge Villafana and Zarek Valentin to spring counterattacks with their speedy wingers and midfielders.

X-Factors

Portland Timbers: Bill Tuiloma

The Timbers are going to be a little light at the back thanks to Larrys Mabiala’s red card against FC Dallas. Mabiala has been a major factor in the Timbers defense all season long and his absence will require Bull Poni Tuiloma to step up and cover that huge gap. He popped in and held his own against an increasingly desperate side on Wednesday, but the Seattle Sounders are a different animal. Tuiloma and Liam Ridgewell will have their hands full against Ruidiaz, Nicolas Lodeiro, Christian Roldan, and the entire Seattle attack.

Seattle Sounders: Nicolas Lodeiro

Much like Ruidiaz, Lodeiro represents a most important piece of the Seattle attack against a questionable backline. Lodeiro was third in MLS with 16 assists on the season and will be the one responsible for setting up Ruidiaz and the crew with as many chances as possible. That said, he can find the net himself, as he did eight times in the regular season.

Outlook

This match will be a lot closer than either team would like. Both sides are going to look to get the leg up after one leg, but expect the Timbers to be a little more cautious. They are going to hold back some players in defense as they try to hold back Seattle’s attack. Diego Chara should play a big role here as he looks to cover for the weakened backline. Expect a yellow card from the Colombian defensive midfielder.

The Timbers will look to win the ball back in their own half and spring counterattacks as they hope to take advantage of what will probably be limited chances. They didn’t have much of the ball against FC Dallas and that will probably by the scenario here.

The Sounders, meanwhile, will be allowed to have the ball and will need to be patient and look for gaps in defense. They will have more chances, but efficiency will still be key for them. FC Dallas wasted many good chances with poor shots against the Timbers and Seattle will have to make sure not to repeat that feat.

Both these sides have won MLS Cups recently, so there isn’t any sort of deep history of failure getting in the way. However, it is a big rivalry game, so the pressure from the fans will be quite heavy. This series will be heated and it will offer an atmosphere that cannot be replicated anywhere in MLS. Regardless of how these two matches turn out, grab some popcorn, kick back on the couch, and enjoy what could be the best of the four Conference Semifinal series.