Michael Pineda, who is currently serving a 10-game suspension for using pine tar in a game against the Boston Red Sox, pulled himself from a simulated game on Tuesday because of back soreness.
Pineda, who pitched only one inning in Tampa, felt soreness in a back muscle on his right side.
Tests revealed that he has a Grade 1 strain of the teres major muscle in his back. Pineda probably won't pitch for three to four weeks.
The right-hander is 2-2 with a 1.83 ERA, 1.02 WHIP and 15 strikeouts in 19.2 innings this season.