The reigning MLS champions took out the first leg of the Western Conference final thanks to a double from Keane but he feels it would not be wise for the Galaxy to write off the Sounders at this point of the campaign.
"We can't obviously get too carried away with ourselves. We got a good win tonight, but the job's only half done," he said.
"So if the lads think for one second now this is over, they may think again, because as we know in football, it's a funny old game and anything can happen.
"We'll enjoy tonight, enjoy the win, but as soon as we're back on the training pitch, the focus is on next Sunday."