The Boston Red Sox put backup catcher Doug Mirabelli on the 15-day disabled list after he strained his right calf in the first game of Friday’s doubleheader, the biggest in a series of moves to bolster the team for the pennant race.

Outfielder Wily Mo Pena was traded to the Washington Nationals for a player to be named. Right-hander Clay Buchholz was called up to start the first game against the Los Angeles Angels, which Boston won 8-4, then was sent back down for the nightcap, a 7-5 Angels victory.

To fill the roster spots, the Red Sox called up outfielder Jacoby Ellsbury and catcher Kevin Cash from Triple-A Pawtucket.

Meanwhile in Detroit, during a tense pennant race, the Tigers called up touted prospect Cameron Maybin on Friday and cut slumping outfielder Craig Monroe, a key member of their World Series team last season.

The 20-year-old Maybin, with only six games of experience at Double-A, was set to make his major league debut Friday night against the New York Yankees – weather permitting. He was in the starting lineup, playing left field and batting second.

Drafted 10th overall in 2005 out of high school in North Carolina, the multiskilled Maybin is considered one of the top prospects in baseball.

In fact, Tigers general manager Dave Dombrowski, who also built winning teams in Montreal and Florida, called him the best position-player prospect he’s had in any organization.