[CONCACAF CHAMPIONS LEAGUE] For the first time since the launch of the Concacaf Champions League, two MLS teams will be in the semifinals.

Just like the Seattle Sounders, who got a key goal from homegrown rookie DeAndre Yedlin in their comeback win over Tigres on Tuesday night, the Los Angeles Galaxy got goals from teenagers Jose Villarreal and Jack McBean to join the Seattle Sounders in the final four with a 4-1 win over Herediano on Wednesday.

U.S. international Herculez Gomez ended the Houston Dynamo's hopes to reaching the semifinals with the decisive second goal -- his eighth, all against MLS clubs, in Concacaf play -- in Santos' 3-0 win over the Dynamo that erased the MLS club's 1-0 advantage from the first leg.

The results set up a pair of USA-Mexico matchups: Seattle Sounders-Santos and LA Galaxy-Monterrey.

Omar Gonzalez jumped high above the Herediano defense to put away Juninho's corner kick in the 18th minute, but it was Villarreal, back from U.S. U-20 duty, who broke the game open when he eluded his defender and fired a shot past Herediano keeper -- almost a carbon copy of his first professional goal for the Galaxy last summer against Vancouver.

After Robbie Keane and Elias Aguilar exchanged goals, McBean put the game away with his fourth goal of the competition in stoppage time.

Juan Pablo Rodriguez (who was briefly on the books of MLS's San Jose Clash) put Santos ahead in the 23rd minute, and Gomez added to its lead five minutes later when he beat Bobby Boswell to the ball before firing a shot past Tally Hall.

The Dynamo was still in the hunt for a goal at Torreon that would have given it the away goal it needed to regain the series edge on aggregate, but Marc Crosas blasted Osmar Mares' cross past a helpless Hall at the far post in the 77th minute to end the suspense.

The semifinals will be played over two legs April 2-4 and April 9-11.

LA Galaxy-Herediano Highlights: