(Ralph Freso / AP)

Stephen Strasburg threw a clean bullpen session without any issues on Thursday morning in Denver and was cleared by Nationals trainers, according to Manager Davey Johnson. Strasburg is still on track to come off the disabled list on Sunday from a lat muscle strain and start in Cleveland, Johnson said.

Strasburg threw 56 pitches and faced hitters in a simulated game on Tuesday and said he felt no tightness in his side. Strasburg last started on May 31 when he left after two innings because of the discomfort in his lower back. The Nationals rotation hasn’t been complete since then, as Ross Detwiler, who starts Thursday, had been out since May 15. Now, the rotation is nearly whole again.

“It gives me a little more comfort feeling,” Johnson said. “[Rookie call-up] Nathan Karns pitched pretty good for a youngster but you can’t hardly replace a Detwiler or a Strasburg.”

Right-hander Ross Ohlendorf, who delivered six brilliant innings in his start on Wednesday, will stick around as long reliever but also a backup starter should Strasburg, or others, suffer any setbacks.