BOSTON -- After J.D. Martinez exited Thursday's 7-2 loss to the Tigers in the top of the eighth inning with tightness in his back, the Red Sox slugger was not in Friday night's lineup against the White Sox.

However, manager Alex Cora -- who had been looking to get the slugger a day off at some point soon anyway -- expects Martinez will be back in there on Saturday.

"Yeah, just giving him a day, I was actually looking for a day throughout the weekend," Cora said. "I took him out because of the back [Thursday] so it makes sense to try to stay away from him today and then he'll be back tomorrow."

Martinez tried to lobby his way into Friday's lineup, but Cora opted to be conservative.

"You know, we texted him in the morning and he was pushing hard but I was like, 'Nah, this is for the long run' and I don't feel comfortable just sending him out there and all of a sudden he gets tight again and he feels it a little bit and I have to take him out," Cora said. "Get treatment, hang out with [trainer] Brad [Pearson] for a while, and then hit whatever he's going to hit tomorrow."

Brock Holt played right field Friday and batted second in Martinez's absence.

Playing short-handed has been a regular thing for the Red Sox lately. Star right fielder Mookie Betts hasn't played since May 27 due to a left abdominal strain and second baseman Dustin Pedroia played just three games in his return from left knee surgery before landing back on the DL last weekend.

Betts is inching toward a return, which will likely include a short Minor League rehab assignment once he is swinging with "conviction" as Cora put it.

"It might be today. It might be tomorrow. Yesterday it was OK," Cora said. "Hopefully, today it's better. He's been doing a lot of stuff here that made us think the BP part of it, the baseball part of it, was going to take care of itself. But sometimes it doesn't work that way. He's been very aggressive in the weight room and everything he's doing. It's just a matter of him feeling comfortable and he can swing with conviction. When that happens we'll make a decision."

And Pedroia?

"He's done a few [baseball activities]. Not like full blast," Cora said. "He still has some inflammation in the knee so we'll take it day by day. Like everybody else, we're not going to push him. We know how important he is to us. We just have to make sure he's ready. Whenever he's ready, he's ready."

Ian Browne has covered the Red Sox for MLB.com since 2002. Follow him on Twitter @IanMBrowne and Facebook.