CONCACAF Champions League: LA Galaxy left bitterly disappointed by performance vs. Isidro Metapn

The LA Galaxy weren't very happy after wasting a chance Thursday night to set up a quarterfinal matchup to their liking in the CONCACAF Champions League.

They conceded four first-half goals, all by Nicolas Muñoz, en route to a stunning 4-0 defeat at Isidro Metapán in the competition's final first-phase game, slumped to sixth among the eight group winners, and were paired with Club Tijuana for next March's quarterfinals.

“Certainly a disappointing performance by our team ...,” head coach Bruce Arena told reporters in San Salvador, El Salvador, in a brief postgame news conference. “Really disappointed with our team's performance.”

The Galaxy, using a largely reserve lineup, as they often do in the competition, offered little on the attack, defended poorly, and were outclassed all over the field by a side that had nothing more than pride to play for.

Muñoz scored in the 29th, 30th, 33rd and 41st minutes, and the Galaxy, who could have snagged the No. 1 seed with a runaway victory, were finished.

“It's heartbreaking,” Galaxy midfielder Rafael Garcia said. “This is a group [of lesser-used players] that's been together for quite some time this year. We got a result out in Costa Rica [last month to clinch the group title]. Tonight it didn't go our way for whatever reason.

“I'll take blame for it. I thought we could have reacted a bit differently, and a lot of guys that needed to step up tonight didn't, including myself. It's tough. You've got to learn from this and step forward.”

Muñoz's first goal, a free kick from the left flank that beat goalkeeper Brian Rowe at the near post, startled LA. The second arrived just 89 seconds later, and then the third a few minutes after that, both of them aided by lax defending.

“I think after a goal like that you give up, everyone's head just dropped, kind of,” said defender A.J. DeLaGarza, who was beaten on two of the strikes. “Credit to them. They kept pushing us and pressuring our backs to get the ball. It was tough to keep it on this field, [but] with that being said, I thought they kept it pretty damn well.

“It's a field where the bounces either go your way, or they don't, and I think on a couple of goals, they didn't go our way.”

Arena was asked if the Galaxy, who have a critical battle Sunday at Seattle in their MLS regular-season finale, had overlooked Metapán.

“I did not underestimate the opponent,” he replied. “And if our team did, it certainly showed.”

Had the the Galaxy won a top-five seed, they would have drawn one of the other MLS clubs to advance to the quarterfinals, San Jose or Kansas City, or Panama's Arabe Unido or Costa Rica's Alajuelense. Instead, they get the 2011 Liga MX Clausura champion and might need to beat all three remaining Mexican clubs – Toluca and Cruz Azul are the others – to win the trophy.

“It doesn't really matter who you play,” DeLaGarza said. “You've got to beat three teams to win the entire thing, so I don't think it matters where you start. ... We've just got to play well next year and win it.”