The 2014 MLS Cup winners produced a fairly routine performance to down the visiting Fire 2-0 at the StubHub Center in Carson, California in front of a sellout crowd of 27,000.
Villarreal's opener came in the 65th minute when he pounced on a defensive error from Fire defender Jeff Larentowicz to lash a left-footed effort past a hapless Sean Johnson.
Ex-Tottenham striker Keane, the 'King of LA', then added a second with nine minutes remaining when getting on the end of a clever header from Baggio Husidic to slam home a classy volley.
LA produced the better of the chances throughout the night although Chicago had a shout for a penalty early in the second half when Robbie Rogers tracked back to defend Quincy Amarikwa who was knocked off the ball.
Nevertheless, the Galaxy deserved their win which extended their unbeaten run at StubHub to 21 in all competitions and will now look ahead to next weekend's trip to Portland Timbers as Frank Yallop's Fire host the Vancouver Whitecaps.
2015 MLS season scores
StubHub Center, Carson, California - 27,000
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