Tension hung in the air last night as the Seattle Sounders moved

Tension hung in the air last night as the Seattle Sounders moved past FC Dallas in the Western Conference semifinal match of the MLS Cup Playoffs at home. The score was zero-zero, with Seattle getting a pass-through to the finals on a new away-goal tiebreaker rule.

That doesn’t mean there wasn’t a lot of action, though. Seattle repeatedly created opportunities to score, with 14 attempts on the Dallas goal during the night. Two of the closest moments came from forward Clint Dempsey in the 41st and 84th minutes, both blocked by Dallas goalkeeper Chris Seitz.

But Dallas couldn’t put it away either as Seattle’s back line held its ground, buoyed by the efforts of All-Star defensive candidate and center back Chad Marshall. The performance, which repeatedly smothered an aggressive Dallas attack, allayed concerns that have dogged the team all season: that its defense wasn’t good enough.

The team moves on to face long-time conference rival L.A. Galaxy in the finals at the end of the month. The Galaxy destroyed Real Salt Lake 5-0 in the second leg of their own semifinal matchup.

View the full slide-show of Monday’s game here.

Fans react to the heavy tension in the last fifteen minutes of the match.

Fans react to the heavy tension in the last fifteen minutes of the match.

Seattle forward Obafemi Martins reacts to a missed attempt on goal in the second half.

Seattle forward Obafemi Martins reacts to a missed attempt on goal in the second half.

Seattle goalkeeper Stephan Frei reaches for the ball in the second half.

Seattle goalkeeper Stephan Frei reaches for the ball in the second half.

Martins, left, battles for control with a Dallas defender in the second half.

Martins, left, battles for control with a Dallas defender in the second half.

Sounders' forward Clint Dempsey attempts to break past Dallas defenders in the first half.

Sounders’ forward Clint Dempsey attempts to break past Dallas defenders in the first half.

Dallas goalkeeper Chris Seitz dives to block a Sounder's attempt on goal in the first half.

Dallas goalkeeper Chris Seitz dives to block a Sounder’s attempt on goal in the first half.

Seattle's Martins works past a Dallas FC player for a shot on goal in the first half.

Seattle’s Martins works past a Dallas FC player for a shot on goal in the first half.

Seattle midfielder Osvaldo Alonso grimaces in pain, holding his hamstring. He left the game.

Seattle midfielder Osvaldo Alonso grimaces in pain, holding his hamstring. He left the game.

Seattle forward Obafemi Martins tries to break past a Dallas defender as he works toward the goal in the first half.

Seattle forward Obafemi Martins tries to break past a Dallas defender as he works toward the goal in the first half.

Fans cheer in the first half.

Fans cheer in the first half.

Dallas goalkeeper Chris Seitz pulls down a Sounders shot on goal in the first half.

Dallas goalkeeper Chris Seitz pulls down a Sounders shot on goal in the first half.

Seattle midfielder Gonzalo Pineda signs autographs for fans after the match.

Seattle midfielder Gonzalo Pineda signs autographs for fans after the match.

Fans cheer the Sounders in the first half.

Fans cheer the Sounders in the first half.

Sounders FC player Obafemi Martins works the ball past FC Dallas defender Zach Lloyd's flying leap.

Sounders FC player Obafemi Martins works the ball past FC Dallas defender Zach Lloyd’s flying leap.

Dallas defender Moises Hernandez grabs the shirt of Seattle forward Obafemi Martins as Martins works toward the goal in the first half.

Dallas defender Moises Hernandez grabs the shirt of Seattle forward Obafemi Martins as Martins works toward the goal in the first half.

Martins tries to break away from a Dallas defender in the first half.

Martins tries to break away from a Dallas defender in the first half.

Midfielder Gonzalo Pineda takes a fall after battling for control with a Dallas defender in the first half.

Midfielder Gonzalo Pineda takes a fall after battling for control with a Dallas defender in the first half.

Seattle forward Obafemi Martins looks for a call from the referee in the first half.

Seattle forward Obafemi Martins looks for a call from the referee in the first half.

Clint Dempsey, Sounders star forward, works up the field toward the goal in the first half.

Clint Dempsey, Sounders star forward, works up the field toward the goal in the first half.

Seattle midfielder Osvaldo Alonso battles for the ball against a Dallas defender.

Seattle midfielder Osvaldo Alonso battles for the ball against a Dallas defender.

The Supporters' Shield is held up by members of the ECS fan club during the March to the Match pre-game celebration.

The Supporters’ Shield is held up by members of the ECS fan club during the March to the Match pre-game celebration.

Fans sing support songs during a March to the Match rally before the game.

Fans sing support songs during a March to the Match rally before the game.

Sounders fans prepare to take part in the March to the Match celebration before the game.

Sounders fans prepare to take part in the March to the Match celebration before the game.

A fan kisses the Supporters Shield, won each season by the team with the best regular season record. Seattle won it for the first time in 2014.

A fan kisses the Supporters Shield, won each season by the team with the best regular season record. Seattle won it for the first time in 2014.