Robbie Keane scored a first-half hat-trick as Los Angeles Galaxy cruised to a 4-0 win over Seattle Sounders at The Home Depot Center.

The Galaxy took the lead in the 12th minute as Keane played a one-two to get behind the Seattle defence and passed the ball across the face of goal where Sean Franklin was on hand to tap it into the net.

The home side doubled their lead when Landon Donovan's cross from the left wasn't cleared by the visitors and the ball deflected into the path of Keane, who fired his shot into the bottom corner.

Keane could have notched a second minutes later but his shot from the left was well saved by Michael Gspurning.

However, Keane did get his second and the LA's third goal of the game when he converted a penalty after Gyasi Zardes was brought down in the box by Djimi Traore.

He scored on the second attempt after his first kick was retaken when Gspurning advanced too far off his line to make a save.

The home side were awarded another penalty after Juninho was brought down by Brad Evans. Keane duly stepped up again and sent Gspurning the wrong way to secure his hat-trick and score his side's fourth goal of the game.

After the break, the Galaxy were content to sit on their comfortable lead but could have added a fifth if not for a good save by Gspurning to deny Donovan, as he tipped his shot over the bar.

Seattle looked for consolation but couldn't find a breakthrough as the hosts saw out a comfortable win.