Minnesota Twins ace Pablo López will miss at least the next two months, and perhaps closer to three, after suffering a grade 2 strain of the teres major muscle in his right shoulder, the club announced Wednesday night.

It’s a tough blow for the Twins’ rotation, which has been among baseball’s best this season. López has been a big reason why, with a 2.82 earned-run average across his 11 starts. To fill his place in the rotation, the Twins called up David Festa, who started on Thursday and gave up eight runs in 3⅔ innings against the Athletics.

Minnesota Twins right-hander Pablo López is expected to be sidelined 8 to 12 weeks because of a strained shoulder. The Twins said Wednesday that López has a Grade 2 strain of the teres major muscle.