Toronto second baseman Devon Travis was at the plate vs. right-hander Rick Porcello when he hit a foul ball off DiMuro's mask. DiMuro fell down to one knee and was then looked at by Blue Jays head trainer George Poulis.
Following a rather lengthy delay, DiMuro eventually walked off the field under his own power, but he was being closely followed by the training staff of both teams. He was replaced by second-base umpire Brian Gorman as the game went ahead with three umpires.
The official time of delay was nine minutes as Gorman needed to put on his gear for duties behind the plate.
Gregor Chisholm has covered the Blue Jays for MLB.com since 2011. Follow him on Twitter @gregorMLB and Facebook, and listen to his podcast. This story was not subject to the approval of Major League Baseball or its clubs.