Hammond, Ind. ? Lawrence’s Bob Glass was forced to withdraw from the PBA Senior Tour’s Lake County Open on Thursday morning because of an injured right knee.

“It’s my good knee that went out,” Glass said. “I don’t know what happened.”

Glass, who wears a brace on his left knee, was in his third game of match play Thursday when his right knee buckled.

“I felt pain. Then I rolled again to pick up a spare,” he said, “and it was really, really painful.”

Glass, a two-time PBA Senior Tour player of the year who ranks No. 2 on this year’s money list, had planned to go to next week’s final Tour stop in Jackson, Mich., but concedes he may have to return to Lawrence.

“I iced it and the swelling went down,” Glass said Thursday afternoon. “I’ll bowl on it tomorrow and if it’s OK, I’ll go there. If not, I’ll come home.”