Houston Astros right-hander Lance McCullers Jr. is no longer throwing off the mound and is back to throwing on flat ground in his bid to return from a muscle strain in his forearm.

McCullers, who first experienced soreness in the forearm in February, had been throwing bullpen sessions earlier this month. He has yet to pitch in a game this season.

"We have to take it slow with Lance until we know that he's 100 percent. That's where it is right now," Astros manager Dusty Baker told reporters Monday.