Anaheim, CA -- (Sports Network) - The Boston Red Sox recalled Justin Masterson from Triple-A Pawtucket on Sunday prior to the club's 5-3 loss to the Angels.

This marks Masterson's fourth stint with the big-league club, having gone 4-3 with a 3.67 earned run average in nine starts with Boston earlier this season. The Sox brass have made it clear Masterson is returning in a relief role following the return of Clay Buchholz from the disabled list

To make room for Masterson on the roster, the Sox placed pitcher David Aardsma on the 15-day disabled list, retroactive to July 19, with a right groin strain. Aardsma is 3-2 with a 2.75 ERA in 38 relief appearances with Boston this season.