Reyes managed to steal his second base of the season, but jammed his head into Utley's left knee with a headfirst slide and appeared to be a bit woozy.
After a few minutes with the trainer, Reyes remained in the game and wound up scoring on an RBI triple to center field by David Wright, giving the Mets a two-run lead and eventually a 6-4 victory.
"He was disoriented and dazed," Mets manager Willie Randolph said. "I told him, 'Talk to me.' He wasn't responding. I said, 'Jog a few steps, or I'm going to take you out.' He said, 'No, no, no, you can't do that.'"
Reyes -- who missed a pair of games last week with a strained left hamstring -- said he needed a few minutes to gather himself.
"I went into space for a little bit," Reyes said.
Utley was glad to see Reyes remain in the game.
"He was out of it a little bit," Utley said. "I didn't know what happened. Nobody wants to see a guy hurting like that. Fortunately, he's OK."
Andy Jasner is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.