Jacoby Ellsbury may have reinjured his ribs while colliding with Rangers pitcher Tommy Hunter. (AP)

Red Sox center fielder Jacoby Ellsbury left his team’s game against the Rangers in the bottom of the fourth inning due to what the team described as “left side pain.” Ellsbury — who was batting leadoff for the first time in five games — incurred the injury while leading off in the top of the first inning. On a dribbler between the pitcher’s mound and first base, Rangers starter Tommy Hunter fielded the ball and lumbered to first base to record the unassisted out.

Hunter was running in the base path, where Ellsbury could not get around him. Ellsbury bumped into the pitcher and then tumbled to the ground, resulting in the pain to an area that has wiped out much of the center fielder’s season.

“There’s certainly some concern there,” Sox manager Terry Francona told NESN. “He managed to fall right on the same spot, trying to stay out of the way of a collision. His arm got caught in there when he hit the ground. We’re going to send him out to LA tomorrow, as quickly as possible. [Red Sox team medical director] Dr. [Thomas] Gill has already examined him. They’ve MRI’d him there. I’m sure they’ll do it all over again and try to get an opinion on where we are as quick as we can.”

The Sox later clarified that Ellsbury would be sent back to Boston to receive his MRI at Mass General. Ellsbury missed 98 of his team’s first 107 games due to five rib fractures. He was hitless in three at-bats on Friday, and is hitting .192 with a .485 OPS for the year.

Jed Lowrie also left the game in the ninth inning due to heat exhaustion, and required treatment with intravenous fluids.

ANAHEIM, Calif. — Red Sox second baseman Dustin Pedroia, out since fracturing the navicular bone on his left foot on June 25, visited with Dr. Lewis Yocum on Tuesday. While the 2008 MVP was told that he continues to progress well in his recovery, and remains ahead of schedule, he was also told that he will need to slow down his efforts to push through any discomfort to return to the field.

Pedroia was warned that he must let the injury fully heal before he begins playing. If he does not, then he would risk another, potentially worse break that would threaten the rest of this season and perhaps his future.

“It kind of scared me a little bit,” said Pedroia. “There’s nothing really I can do. It’s just time it’s got to heal. He kind of told me I can’t play unless I feel no pain, which isn’t good. He did say that when I do my next CT-scan, we’ll be able to tell a lot more. Hopefully that’s good. … Where I broke it, I didn’t realize how serious it was and how long it was going to take.

“I thought I could play, that if I feel hurt, you can just play through it. You really can’t do that with this injury. That’s hard to deal with. That bone will break off, then they would have to put pins in it. It would be a disaster. It could go into the offseason and then maybe next year,” he added. “I want to get back more than anyone in the world and play, but I don’t want to do anything stupid where I can never play again. I’ve got to lay out rockets, man.”

Pedroia tried doing some running on Monday, and still felt discomfort at the point of the fracture. Yocum cautioned him that he could not push through that sort of pain, and instead had to avoid activities that led to that sort of discomfort.

After the consulation, Pedroia said that he was unsure what the timetable of his return might be. He is still hoping that he might be able to make it back within the six-week prognosis that he was given (Aug. 6 represents the six-week mark), but he admitted that he was uncertain whether that remains realistic. He will find out more when he undergoes a CT-scan on Friday back in Boston.

“Everything looks great. I’m ahead of schedule. It’s just my schedule and their schedule were a little different,” said Pedroia. “I don’t really know how long it’s going to be. They said six weeks at the start, but I have yet to meet somebody who has come back in six weeks from this injury. I’m trying as hard as I can to do that.”

Pedroia is hitting .292 with a .370 OBP, .502 slugging mark, .871 OPS and 12 homers in 73 games.