Chase Headley then flew out to Jason Heyward in right. Castro hesitated, but he then sprinted home. Heyward got the ball to Contreras in time, and Castro and the catcher collided, with Castro's right shoulder hitting Contreras in the face.
"When the line drive was hit, [Castro] hesitated, and I thought he was going to stay on third," Contreras said. "Once the throw was made, all my focus was on the throw. I didn't expect [Castro] to come home. I'm good, I'm fine."
Castro knew he hit Contreras hard, and he felt if he tried to go behind the catcher, he might have had a chance to score.
"We were going in the same direction," Castro said. "I think if I go the other way, I might be safe."
Contreras fell to the ground and was attended to by athletic trainer PJ Mainville and manager Joe Maddon. After a few minutes, Contreras was able to get up and walk off the field under his own power.
"It's baseball," Contreras said. "Those things are going to happen once in a while. It wasn't intentional."
Carrie Muskat has covered the Cubs since 1987, and for MLB.com since 2001. She writes a blog, Muskat Ramblings. You can follow her on Twitter @CarrieMuskat and listen to her podcast. This story was not subject to the approval of Major League Baseball or its clubs.