The Irish national team striker showed off his trademark cartwheel-somersault goal celebration to fans on a new continent after he converted a pass from David Beckham. Keane was active and aggressive in his debut while playing into the 72nd minute.
Los Angeles acquired Keane on Monday from Tottenham Hotspur, putting the 10th-leading goal-scorer in Premier League history alongside Beckham and captain Landon Donovan. Keane appeared to fit in immediately, generating several good scoring chances in addition to his goal.
Mike Magee also scored in the 90th minute for the league-leading Galaxy (14-3-9), who moved six points clear of second-place Seattle in the Western Conference standings with their fifth win in six games. Los Angeles has lost only once since May 1.
San Jose defender Steven Beitashour was ejected in the 81st minute for stepping on Donovan in the latest bad behavior in this California Clasico rivalry match.
The Galaxy fans welcomed Keane with the same enthusiasm shown by the club on Friday, when it flew the Irish flag above the pitch and painted bright-green shamrocks into the grassy berm below the scoreboard. Keane's No. 14 Galaxy shirt already was selling briskly at souvenir stands, and a few Keane shirts from Tottenham appeared in the crowd.
Los Angeles was MLS' best team even before the arrival of Keane, who's already providing a new dimension to its attack. The Galaxy has struggled to get consistent scoring from its forwards, but Keane was a factor from the opening minute, when fellow forward Adam Cristman rang a shot off the far post.
Keane had two decent runs at the goal in the first 15 minutes, but was called offside on both. Keane then barely missed an open shot from the penalty dot in the 19th minute, pushing a left-footed shot wide on a deflection from Cristman. Keane went flat on his back in frustration, but the Angel City Brigade supporters behind the net still cheered him.
Moments later, Keane found himself alone behind San Jose's defense, which failed to clear a through ball from Beckham. Keane waited out Quakes goalie Jon Busch, fired home a left-footed shot and broke into a slightly rusty rendition of his goal celebration, capped by his two-handed gesture at his newest fans.
Keane nearly added another goal in the 64th minute when he outran two defenders to a bouncing pass, but his volleyed shot sailed just over the crossbar.
Magee eventually replaced Keane, who left the field to a standing ovation from the crowd of 27,000.
The rivalry match again featured physical play, culminating in Beitashour's ejection. Donovan made a tackle and slid underneath Beitashour, whose spikes connected with Donovan's knee when he landed.
San Jose and Los Angeles played to a contentious 0-0 draw in late June, with Magee playing goal for Los Angeles for 47 minutes after starter Donovan Ricketts broke his arm and backup Josh Saunders was ejected.