The Red Sox will be without right-handed reliever Justin Slaten for the rest of the season after doctors found degenerative changes in his right flexor mass. Interim manager Chad Tracy announced the decision before Boston's series opener against Texas, and MLB reported that Slaten will receive a platelet-rich plasma injection and begin rehabilitation.

Slaten was placed on the injured list with right elbow inflammation on Aug. 16. His throwing program stopped after symptoms continued, and the latest examination removed the possibility of a September return. The 29-year-old posted a 4.60 ERA with 39 strikeouts in 31 1/3 innings over 36 appearances.

The loss affects how Boston builds the bridge to closer Aroldis Chapman. Slaten and Garrett Whitlock had served as the club's top right-handed setup options when both were unavailable. Whitlock returned Aug. 29, but the bullpen still has to cover Slaten's cleanup innings between the sixth and seventh.

Tracy said the injury could create opportunities for Wyatt Olds or Tanner Houck, who was on a rehab assignment with Triple-A Worcester. Right-hander Tyron Guerrero's return was also delayed by lower-back cramping after he had been expected to come off the injured list. Those developments leave the staff deciding which arms can handle leverage while the club plays nearly every day.

Boston's 4-3 win over Texas on Thursday improved the club to 83-70, but the relief question carries into Friday's series opener at Tampa Bay. The Red Sox must decide whether to shorten the bridge to their established late-inning arms, promote another pitcher, or use Houck and other starters in relief.

Slaten's injury is separate from Ceddanne Rafaela's quad strain and the position-player roster questions. It is a pitching availability problem with a clear consequence for Chad Tracy's matchups during the final weeks of the wild-card race.