Sonnanstine, who has been the Rays' long man out of the bullpen, was pressed into action as a starter on Tuesday night against the Indians, and he allowed two runs in 3 1/3 innings, walking five and using 68 pitches.
"I anticipate he's going to pitch well," manager Joe Maddon said. "He needs to get stretched out. He threw 68 pitches last night, which going to the next start should make him a little bit stronger. We'll see how that all plays out.
"Sonnie's done that in the past. Sometimes he'll look not so good, then all of a sudden he'll rebound and look really good. He doesn't carry negative stuff with him a lot. And, because of that, I think you're going to see a good outing on Sunday."