ARLINGTON -- Red Sox closer  was unavailable to pitch in Boston’s 4-3 win over the Rangers on Thursday at Globe Life Field due to lat tightness and is considered day to day.

“We're going to be conservative with [it],” interim manager Chad Tracy said postgame. “It's getting better, but we're going to make sure it gets there. That's why he wasn't available tonight.”

According to Tracy, Chapman has been dealing with the tightness for the last couple of days, so the team will continue to evaluate him. 

“Obviously, you guys know how diligent he is about his prep and getting in and getting treatment. So we'll just monitor it day to day,” Tracy said.

On Thursday, Garrett Whitlock came in to close out the game, getting a groundout to first, issuing a walk and inducing a 6-4-3 double play to end it.

“[Whitlock is] great,” Tracy said. “He's reliable. He's done it before. If Chappie's down, he's very reliable in any spot we put him in.”

Through 51 games, Chapman owns a 1.95 ERA and a 1.14 WHIP, with hitters batting .190 against him. His 34 saves are tied for third in the AL and tied for fifth in the Majors. He is MLB’s all-time leader in relief strikeouts with 1,399.

Chapman’s absence Thursday was the latest injury concern for a Red Sox team that has had to rely on its depth throughout the season, with eight pitchers currently on the IL. Despite the injuries, Chapman has been impressed by the way younger players have responded when given opportunities.

“They’ve come in because of all the injuries we’ve had, and they’ve been able to do an excellent job,” Chapman said in Spanish on Wednesday. “Now, some players have also returned from their injuries, but because of their youth and the limited playing time they’ve had, they’re doing a very good job with what has been asked of them.

“We always keep playing until the end because you never know what can happen, but [to see that from them] keeps me positive all the time.”