On the game-winning play, the Galaxy's Jaime Penedo failed to control a Dan Gargan throw-in inside the six-yard box. Rookie forward Mark Sherrod stole the ball and found Barnes, who finished with the inside of his right foot to the far post for Houston (5-5-2).
“It was a great finish, if Giles puts it somewhere else it could've been blocked so he hit the perfect spot,” Houston Coach Dominic Kinnear said. “Sometimes is just taking advantage of mistakes and that's what we did tonight.”
L.A. (2-3-3) nearly forced Houston into a miscue in the first half. Off another throw-in, L.A. forward Robbie Keane passed the ball to a wide-open A.J. DeLaGarza. The right back drove into the box and beat on-rushing goalkeeper Houston goalkeeper Tally Hall.
In his spot, however, was center back David Horst, who got to the goal line and headed the chance over the goal to keep the game scoreless.
“If they score it changes everything and the save changes everything,” Hall said. “It goes by me and I think it's going in and Horst is smashing it with his face over the bar. It's brilliant.”
It was a night of missed chances for L.A. as midfielder Samuel Rosa came inches from giving the visitors the lead only 19 seconds into the game. Midfielder Juninho had three chances from distance, two in the first half and one in the second, that were all stopped by Hall.
In the closing minutes, Keane found space before he found the side-netting to give L.A. another close but empty call.
“We just didn't finish; it's hard to believe they even got a goal tonight,” Galaxy Coach Bruce Arena said. “They weren't going to get a goal and we gave them a chance and to their credit they finished it.”
The game may have World Cup implications for the Honduran national team as Boniek Garcia left the game with what Kinnear said was a minor hamstring injury in the 18th minute.
Attempting to make a pass, the Honduran mainstay pulled up and immediately asked for a sub. Garcia was scheduled to join the Honduras team Sunday for World Cup preparations, but will now leave Monday.
“I'm not worried,” Garcia said through an interpreter after the game. “After being taken a look at by the doctor for 20 minutes it was more precautionary than anything.”
Three World Cup hopefuls for the U.S. -- Houston's Brad Davis and L.A.’s Landon Donovan and Omar Gonzalez -- missed the game as all three are with the national team in their pre-tournament camp in Palo Alto, Calif.