CARSON, Calif. - The LA Galaxy spent most of a tense, chippy match deep in Seattle's end, and Marcelo Sarvas finally drove home the goal that put them on top of the Western Conference championship series.

The Galaxy realize they've got much more work to do when these MLS powers head north next weekend to finish their season-long rivalry.

Sarvas scored in the 52nd minute, and the Galaxy opened the conference finals with a 1-0 victory over the Sounders on Sunday.

Jaime Penedo posted his third straight shutout for the Galaxy, who still haven't conceded a playoff goal this season.

Landon Donovan, Robbie Keane and the Galaxy also haven't lost at home since their season opener in March, and they kept the Supporters' Shield-winning Sounders off the scoresheet in a match filled with these teams' usual fouls and ferocity.

"I wouldn't say we're comfortable, but it's a good position," Keane said. "The most important thing today was not to concede a goal, and we also managed to get one."

The clubs play their second leg Nov. 30 on Seattle's artificial turf. The Galaxy could advance with a variety of results, since the tiebreaker is away goals.

The winner hosts the MLS Cup on Dec. 7.

"We're full of confidence going there," said Donovan, who will retire after the season. "It's going to be even more physical next week, and that's OK. We can handle that."

Seattle played without forward Lamar Neagle, who left the team "to deal with a serious personal matter," according to a statement. The Sounders also didn't have midfielder Osvaldo Alonso, who sat with a hamstring injury.

Seattle stars Obafemi Martins and Clint Dempsey both had a handful of opportunities, but the Galaxy kept their sheet clean. The Sounders' frustration was encapsulated when Penedo made a spectacular double save against close-range strikes by Martins and Dempsey in the 20th minute.

"It was a back-and-forth game," Dempsey said. "I thought we should have been able to score. I thought I should have scored, but at the same time, we're only going to get more players back (next week). We're still confident."

The Sounders and the Galaxy were clearly MLS' two best teams in the regular season, which ended with a home-and-home series between the powers last month after LA nearly rallied all the way back to the top of the table. But the Sounders overcame a two-goal deficit to tie the clubs' match at Carson before clinching the Supporters' Shield with a win at home.

In the post-season, both teams traded hard fouls and shoves with their usual physical style. Martins, Dempsey, Keane and Robbie Rogers all missed on golden chances, and players from both teams were roughed up.

"It was the same as it was a few weeks ago with them," Keane said. "Certainly there was a lot of persistent fouling, more so from their side."

The Galaxy finally scored when A.J. De La Garza got it into the box for Sarvas, whose shot deflected off Chad Marshall and past Stefan Frei for his second post-season goal.

After LA's Stefan Ishizaki put a free kick off Frei's crossbar moments later, De La Garza left the game with hamstring pain. Sarvas also was helped off the field in pain in the 68th minute, appearing to favour his left leg.

With Seattle's defence targeting him, Donovan had a quiet afternoon following his hat trick in the LA's clinching 5-0 victory over Real Salt Lake in the last round. The Galaxy ran much of their offence through Ishizaki, while Donovan and Keane couldn't convert their few chances.

"We created four really good chances, even after we were down," Seattle coach Sigi Schmid said. "If we weren't creating chances, I'd be concerned. But we were."