Peruvian international Raul Ruidiaz scored twice as the Seattle Sounders shocked top seeds Los Angeles FC 3-1 to clinch the Western Conference final and book a place in the MLS Cup on Tuesday.

Ruidiaz scored a goal in each half to complete a superb victory for Seattle, who recovered from falling behind to an early Eduard Atuesta goal to reach Major League Soccer's championship game for the third time.

The defeat left Bob Bradley's Los Angeles team shell-shocked after a record-breaking regular season campaign that made them favourites to win a maiden MLS Cup.

However the LAFC's raucous Banc of California Stadium home crowd were silenced by a superbly disciplined Sounders display.

Seattle will now face either Toronto FC or defending champions Atlanta United in the MLS Cup final on November 10. Toronto, who defeated Seattle in the 2017 final, face Atlanta in Georgia on Wednesday.

Tuesday's match had got off to a cagey start, with Los Angeles quickly settling into their slick passing game but unable to create much in the way of goal-scoring opportunities against a well-organised Seattle.

The breakthrough came after 17 minutes, when Los Angeles talisman Carlos Vela surged forward to win a free-kick 25 yards from goal.

The Mexico international stood over the dead ball as if to shoot but instead left the strike to Colombian midfielder Atuesta who duly curled in a sublime strike to beat Stefan Frei.

The Banc of California Stadium erupted and Los Angeles looked to be on a roll. Three minutes later Uruguayan international Brian Rodriguez tested Frei with an angled shot from the left which the Seattle goalkeeper could only parry away. Latif Blessing's rebound was blocked for a corner.

Yet just when it seemed Los Angeles had taken a grip on the game, Seattle roared back into the contest with two goals in four minutes.

Peru's 2018 World Cup striker Ruidiaz got the Sounders back on level terms in the 22nd minute, leaving Los Angeles defender Eddie Segura for dead with a wonderful turn, bursting into the box and rifling home.

Los Angeles had barely digested the shock of the equaliser before Seattle made it 2-1.

Again Ruidiaz was heavily involved, launching a counter-attack which culminated with Uruguayan playmaker Nicolas Lodeiro drilling a low finish past Tyler Miller from the edge of the area.

The killer blow came in the 64th minute, when Lodeiro again supplied the opening for Ruidiaz whose low shot made it 3-1.