Varitek did catch the top of the third, but Doug Mirabelli pinch-hit for him in the bottom of the inning.
After advancing to second on an infield single by Coco Crisp, Varitek hobbled as he crossed the bag.
The captain will undergo further evaluation from the club's medical staff on Tuesday. It goes without saying the Red Sox can ill-afford to lose Varitek for any length of time because of what he means to the pitching staff.
He is currently being listed as day-to-day.
"I'm just hoping I'm being a little overly cautious," said Red Sox manager Terry Francona. "I think 'Tek fought me on it a little bit, but I think [taking him out] was the best thing to do. Obviously, he'll be examined [Tuesday], but I'm just trying to be cautious for the long haul."
The Red Sox have an experienced backup in Doug Mirabelli, who is probably equal to Varitek from a defensive standpoint.
Mirabelli was scheduled to start on Tuesday anyhow, so the Red Sox can be a little conservative with Varitek.
A close friend of Varitek's, Mirabelli has great respect for what the captain goes through on a daily basis to stay in the lineup.
"That's one of the reasons why he's our captain," Mirabelli said. "He goes out there when he's not 100 percent, when he's not even close to 100 percent, and he continues to go out there and fight and give us the best chance to win. For him to put on kneesavers the last couple of games, it was a sign to me at least, that [Varitek was hurting]. I don't know how long this is going to go. He's doing everything possible that he knows and that the trainers know to keep him on the field."
Ian Browne is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.