CLEVELAND, Ohio -- The Indians have, for now, sorted out their rotation, with Corey Kluber returning to the fold.

The right-hander will start Thursday's matinee against Oakland. Danny Salazar's relocation to the bullpen cleared space in the five-man unit. On Thursday, the club optioned reliever Shawn Armstrong to Triple-A to open a spot on the active roster for the ace.

Kluber last started on May 2 at Comerica Park in Detroit, where he exited after three innings because of discomfort in his lower back. The ailment had troubled him for nearly a month, and it cost him nearly another month of his season.

In six starts this season, Kluber has posted a 5.06 ERA, with 41 strikeouts in 37 1/3 innings.

Tribe manager Terry Francona suggested that Kluber would make his next start a week from Friday at Progressive Field. The Indians play at Kansas City this weekend, and then have a pair of off-days surrounding a two-game set in Colorado next week.

As for Thursday's start, Francona indicated that the Indians would ease Kluber back into action.

"He's not going to pitch all day," Francona said. "I guarantee you that. The key is to win, but also set him up for the rest of the year. We'll keep an eye on him. We'll probably aggravate him a time or two by asking him how he's doing."

Armstrong has bounced between Cleveland and Triple-A Columbus like a pinball the last two seasons. He has logged 12 innings with the Indians this season, and he has a 6.00 ERA and 13 strikeouts to show for it.

Mike Clevinger's ascent to the big-league rotation forced the Tribe brass to trim the group by one member.

Salazar's shift to the bullpen -- Francona said he'd be available on Thursday -- gives the club eight relievers. The Indians have operated with a short bench, with outfielders Lonnie Chisenhall, Brandon Guyer and Abraham Almonte all on the disabled list.

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