LA Galaxy maintained their momentum in MLS with a 5-1 thrashing of New York City, the latter suffering the heaviest defeat in their short history.

Robbie Keane struck twice and had two assists in a rampant showing for the StubHub Center hosts, while Gyasi Zardes, Giovani dos Santos and Sebastian Lletget also scored for Bruce Arena's men.

Galaxy's win took them top of the Western Conference on 46 points, one clear of Vancouver Whitecaps - who have a game in hand.

Sunday's fixture was originally billed as a clash between former Premier League rivals Steven Gerrard and Frank Lampard - but the latter withdrew from City's squad due to ongoing rehabilitation with a quadriceps injury.

A defensive lapse from City saw Juninho take a quick free-kick - David Villa the villain - to Keane, who curled in a cross to Zardes to nod home under no pressure in the 36th minute.

Keane then fired home himself with a right-foot chip over the onrushing Josh Saunders eight minutes after the interval, and Dos Santos replicated the Irishman's effort - although he used his left to lift one over Saunders for 3-0 in the 67th minute as City's offside trap was sprung again.

Lletget was on hand to deflect Gerrard's side-footed effort in three minutes later, before Villa scored a consolation penalty for the visitors.

Galaxy had the last laugh, however, restoring the four-goal margin moments later when Robbie Rogers broke free down the left flank, and teed up Keane for a tap in to seal his brace and further City's embarrassment.

City remain outside the top six in the Eastern Conference, level on points with the play-off bound Montreal Impact - but having played four more games than their rivals.