BALTIMORE -- Red Sox manager Francona made it official that Justin Masterson will start today at Fenway Park. He replaces Daisuke Matsuzaka, who is on the 15-day DL with mild rotator-cuff strain, in the rotation. The Red Sox will have to make a roster move to make room for the rookie right-hander, and the manager said that will be announced today. It’s likely Jeff Bailey will be sent back to Pawtucket. He was recalled on Friday and played in two games (one start) during the weekend wraparound series with the Orioles.

This will be Masterson’s third start for Boston this season. He’s 1-0 with a 1.46 ERA in two spot starts. He was dealt a no-decision in his major-league debut on April 24 against the Angels and recorded his first victory on May 20 against the Royals. Francona said he’s excited to see the 23-year-old pitch again, and this time around, Masterson will be able to spend some time around the club since he’ll make more than one start.

jmcdonal@projo.com