Rangers center fielder Dan Robertson leaves game after collision
Robertson dove head first for the ball and Rios slid feet first, and it appeared Robertson's head hit Rios' knee. It also appeared in the slow-motion replay that one of Robertson's teeth flew out of his mouth; Robertson touched near his mouth after it happened.
The team hadn't made an announcement about the injury as of the sixth inning.
Robertson, who is 5-foot-8 and 170 pounds, remained down on the grass as a trainer and manager Ron Washington looked at him. He walked off under his own power.
Leonys Martin replaced him in center field.
A 28-year-old rookie, Robertson was playing in only his ninth major league game after he was recalled from Triple-A Round Rock earlier this week. He picked up his third career hit on Thursday, a single to lead off the game.SI WIRE: Giants starter Matt Cain exits game vs. Rockies with strained right hamstring