BOSTON -- The Rangers were back at full strength on Friday night, when shortstop Michael Young and third baseman Hank Blalock returned to the starting lineup against the Red Sox at Fenway Park.

Blalock left Wednesday's game against the Blue Jays in the 10th inning because of stiffness in his lower back. He did not play on Thursday. Young also missed Thursday's game against the Blue Jays with a sore calf muscle, but he was ready to go on Friday.

"I feel great," Young said. "I think yesterday I could have played, pretty sure I could have gone, but I don't want to do what I've done in the past, which is try and gut it out, next thing I come in the third or fourth and I'm out of the game and we just burned a guy. I was ready to come in late, but fortunately, we had a lead and it didn't have to come to that."

Both injuries weren't helped by the artificial turf of Toronto's Rogers Centre. The Rangers were concerned that Blalock might miss the first two games of the Red Sox series, but he told them that he could play on Friday night.

"I just kind of tweaked it in the late innings of the first game, and then it was real stiff [on Thursday], and playing on the turf would have probably made it worse," Blalock said. "So the smart thing to do, I think, was to take the day off, and that way I could heal up for the rest of the road trip. I woke up this morning and everything felt real good, and I got a lot of treatments, so it loosened up."

The Rangers' next step is to get reliever Eddie Guardado back in the bullpen and see what exactly is wrong with outfielder Marlon Byrd's left knee. Byrd was placed on the disabled list on Thursday because of soreness in the knee, and he will undergo an MRI on Monday.

"It's just not getting any better," Byrd said. "We want to know what this is and get treatment for it. I want to be back in 15 days."

Guardado is on the DL with a sore left shoulder, and he's eligible to come off on Sunday. He is scheduled to have a light throwing session in the bullpen on Saturday.

"If all goes well, he'll be coming off," Rangers manager Ron Washington said.

Josh Rupe, who has a 6.43 ERA in three appearances, could be the leading candidate to be sent down to make room for Guardado.

Right-hander Kevin Millwood also had a bullpen throwing session, and he had no problems with the bruised shin on his left leg. He is expected to start on Sunday. Millwood had to leave his last start after getting hit in the chin with a ball back to the mound.