CHICAGO (AP) — Boston Red Sox right fielder Tyler O’Neill left Friday night against the Chicago White Sox because of right knee discomfort.

O’Neill was just activated from the 10-day injured list on Wednesday after being sidelined by right knee inflammation.

It was unclear when exactly O’Neill was hurt. He flied out for the first out of the second inning. After Lenyn Sosa popped up to catcher for Chicago’s first out of the third, O’Neill walked off the field with manager Alex Cora and a trainer.

Rob Refsnyder, who moved from left to right field as part of a flurry of moves after O’Neill departed, then made a terrific diving catch on Corey Julks’ sinking flyball for the second out of the inning.

O’Neill was acquired by Boston in a December trade with St. Louis. He went on the IL with the knee issue on May 29.

O’Neill, who turns 29 on June 22, is batting .250 with 11 homers and 18 RBIs in 44 games.