Seattle Sounders scored four times before the half-time interval on their way to a 4-2 victory over Chivas USA in Los Angeles.

The Western Conference leaders took control of the contest from the first whistle, breaking the deadlock in the 11th minute when Obafemi Martins met a Chad Marshall header with a powerful finish.

Chivas found it difficult to handle the threat posed by Seattle's attacking players, and were two goals behind five minutes later as Martins linked with Lamar Neagle before firing past a helpless Dan Kennedy.

It was 3-0 to the visitors later in the first half when Andy Rose arrived at the back post unmarked to convert an inviting corner from Brad Evans.

However, the misery was not over for Chivas as Rose scored his second, and Seattle's fourth, by heading home another delivery from the influential Evans.

The hosts produced an impressive response after recovering during the break, with Marco Delgado finding the back of the net in the 51st minute with a free header.

Seattle reduced the deficit further on the hour mark when Ryan Finley slotted home from the penalty spot after being brought down inside the box by Zach Scott.

Chivas continued their improvement throughout the second half, but they missed the chance to set up a dramatic finish when Andrew Jean-Baptiste somehow missed the target with his header from close range.

Seattle held off the challenge from the hosts, and took another step closer to claiming the Western Conference title with the win.