The Rays placed southpaw Matt Moore on the 15-day disabled list on Wednesday after the 14-game winner felt soreness in his pitching elbow.
"The goal is to be healthy for the last month and a half," Moore tweeted. "I'm very optimistic."
Moore also said that an MRI showed no structural damage.
The move is retroactive to Monday, one day after Moore allowed five runs over five innings in a no-decision against the Yankees. The club recalled infielder Ryan Roberts, who is reportedly in Wednesday's starting lineup and playing third base.
A first-time All-Star this season, Moore, 24, has compiled a 14-3 record with a 3.41 ERA in 21 starts. He has tallied 115 strikeouts in 121 1/3 innings.
The Rays enter Wednesday's action with a half-game lead over the Red Sox in the American League East. They have rattled off 21 wins in 25 games in July to move to 64-43, the best record in the Junior Circuit.
Tampa Bay pitchers have tossed seven complete games since July 7 and four in their past eight games, including Moore, who threw a two-hit shutout against Boston on July 22.
Read more: Rays place Matt Moore on 15-day disabled list | MLB.com: News