Morgan takes Jerome Williams' spot in the rotation. He is on the disabled list after he strained his left hamstring in Tuesday's 19-3 loss to the Orioles.
"He's been throwing well," Phillies manager Ryne Sandberg said about Morgan. "I think it will be good to add a left-hander in the mix here, and he's been doing a good job. He's done well. Saw him in the spring with what he had, so I'm anxious to see him."
Morgan, whom the Phillies drafted in the third round in 2011, had been on the fast track in Philadelphia's system before he suffered a left shoulder injury in May 2013.