The victory gave Peter Vermes his 200th coaching win for Sporting in all competitions.
"In the first half," said Vermes, "we played with a lot of courage and we were also excellent when we turned the ball over. I thought Alan was great in between the lines. He brought a lot of guys into the game and gave us a pause to get people forward. At the end, I think it was a really good team performance."
LAFC coach Bob Bradley described the result as a "bad loss," which he blamed not being focused from the start.
"You can't start a game where you've got two, three, four guys that just aren't up to the speed of the game," he said.
The defeat dropped LAFC 10 points off the lead in the Western Conference. It sits in fifth place behind the LA Galaxy, a 1-0 winner over Real Salt Lake, and idle Colorado.