Aybar, who left in the seventh inning after taking a fastball to his right knee from A's reliever Jim Miller, was diagnosed with a bruise postgame and listed as day to day.
Manager Mike Scioscia, who initially expected Aybar to start the series finale at Oakland Coliseum, used Aybar as a pinch-hitter in the 10th inning of Wednesday's 11-inning win over the A's. Aybar flied out to center field.
"It's a little sore," Scioscia said before the game. "Looks like soft tissue on the side of his legs. [Head trainer Adam Nevala] thinks he should be available if we need him late for something, but he's going to get some treatment and hopefully we'll be able to stay away from him."