Early in the inning Sunday, Daley gave up an RBI double to Freddy Sanchez. As the pitcher ran to back up home plate, umpire Bill Welke tossed the bat out of the way to clear space. It landed directly under Daley's left foot on his next stride.
"It was just a freak accident," said Daley, who wore a protective boot after the game.
Daley tried some practice pitches before manager Clint Hurdle and the training staff elected to remove him from the game. The Pirates went on to win 11-4.
"It just really [stinks], to be honest," Daley said. "I just didn't make my pitches I needed to make, and then for that to happen, it doubly negatively affects me."
Daley said X-rays taken on the foot were negative, and the team was characterizing the injury as a sprain. The club said a corresponding roster move to replace Daley would be made later Sunday or early Monday.