Los Angeles FC will host the Philadelphia Union in the MLS Cup final after the top two seeds won their conference finals on Sunday.

Los Angeles beat Austin 3-0 in the Western Conference while in the East, Philadelphia came from behind to beat defending champions New York City FC 3-1.

Neither side have reached the title game before in their histories and Saturday's final, at Los Angeles' Banc of California Stadium, will see the two top seeds face each other in the final for the first time since 2003.

A first-half goal from Colombian striker Cristian Arango, a second-half own goal from Austin's Maxi Urruti and a late strike from Kwadwo Opoku sealed victory for Los Angeles.

LA coach Steve Cherundolo's side will head into the final brimming with confidence after Sunday's composed victory.

"We're excited to be in the MLS Cup final -- that was the objective," Cherundolo said after the triumph.

"I'm very proud of the guys. But there's still hunger and a want for more."

Los Angeles had gone close with good chances failling to Jose Cifuentes and Dwnis Bouanga early on before Arango opened the scoring, nodding in Carlos Vela's corner in the 29th minute.

Los Angeles almost took a decisive advantage shortly before half-time, with Cifuentes's shot from just outside the area well saved by Brad Stuver on 43 minutes.

Vela came within a whisker of doubling the hosts' lead but couldn't get enough on a glancing header from Bouanga's cross.

In the 62nd minute, though, Los Angeles pressure finally paid off.

Vela's in-swinging corner caused confusion in the six-yard box and Austin substitute Urruti headed into his own net for a 2-0 LA lead.

In the 81st minute, substitute Opoku gathered a hopeful ball forward and swept a low shot past Stuver for 3-0.

Austin coach Josh Wolff said his side had been beaten by the better team.

"They were just relentless," Wolff said. "They came at us full throttle and it made it very challenging. It was tough to get a footing. They weren't going to let us get in their half and set up shop.

"When you don't have the ball and you're up against a team like that, they can put you under pressure."

Philadelphia have now gone the entire season without losing at home but that record looked in danger after New York City took a 57th-minute lead.

After a flowing passing move which began with their goalkeeper, Santiago Rodriguez laid the ball off to Maxi Morales who drove a right foot shot into the bottom corner.

It was the first time that Philly had trailed at home since July and they could easily have gone two down but Andre Blake pulled off a brilliant save to keep out a flashing header from Alex Callens.

But City's advantage lasted just eight minutes. New York were caught napping after a substitution as Jakob Glesnes threaded a free-kick through to Julian Carranza, who coolly slotted home.

Two minutes later, substitute Jack McGlynn floated a ball to Carranza in the box and the Argentine headed expertly into the path of Daniel Gazdag.

The prolific Hungarian midfielder, with 22 goals in the regular season, fired past Sean Johnson.

The victory was secured in the 76th minute thanks to the strength and determination of Cory Burke, who wrestled control of the ball in midfield, charged forward before enjoying a little good fortune as Anton Tinnerholm's attempted clearance fell kindly to him and he blasted in the third.

The Union's first Eastern Conference title adds the sports buzz in the Pennsylvania city with the Phillies in baseball's World Series and the Eagles the only unbeaten team in the NFL.

"It's a special time right now in Philadelphia for a lot of reasons," Union coach Jim Curtin said. "But these guys showed they are right up there with the Phillies and Eagles and it's great to see the sport grow this much in this city. I am really proud."