The Rays called up outfielder Wil Myers, rated by Baseball America before the season as its No. 4 overall prospect, best power hitter and best hitter for average.
"We felt like now was the right time," said Andrew Friedman, the Rays' executive vice president of baseball operations. "He made some real adjustments in the last six weeks and that really stood out to us. It was something we were monitoring very closely."
The 22-year-old Myers was acquired from the Royals on Dec. 9 in a seven-player trade that sent pitchers James Shields and Wade Davis to Kansas City. Davis was the winning pitcher in Sunday's game after giving up two runs on five hits in six innings.
After hitting .286 with 14 home runs and 57 RBIs in 64 games at Triple-A Durham, Myers will start at least one of two games at Boston on Tuesday, manager Joe Maddon said.
"He's going to play in the outfield and we'll probably hit him lower in the batting order to begin, just to take a little pressure off of him," Maddon said. "We'll try not to place the expectations too high, although I know it's going to come from outside, not from within. He's another one of our players. I'm going to try to ease him into the whole thing."
Myers will probably make his home debut in the final week of June after the Rays play seven games at Boston and New York.
"It's something that we've been deliberating for a while, and his recent hot streak certainly accelerated the conversations," Friedman said of the move. "As we talked about since spring training, when we felt like he was ready it would be important to auger a spot for him."
Information from The Associated Press was used in this report.