The outfielders both sprinted toward right-center, converging on a Melvin Upton Jr. fly ball to the warning track in the eighth inning of the A's 3-1 loss to the Padres at the Coliseum on Thursday.
"Neither of us called for it," Reddick said. "I think we were both just so committed."
Burns' left elbow slammed into Reddick's face, but that wasn't the worst of the damage. Reddick was also kneed below the belt.
Reddick remained on the ground for a few minutes, as A's manager Bob Melvin and a trainer tended to him.