BOSTON — The Boston Red Sox on Saturday traded shortstop Marco Scutaro and his $6 million salary to the Colorado Rockies while remaining in pursuit of free-agent starter Roy Oswalt.

BOSTON — The Boston Red Sox on Saturday traded shortstop Marco Scutaro and his $6 million salary to the Colorado Rockies while remaining in pursuit of free-agent starter Roy Oswalt.

The Red Sox may be the favorite to sign Oswalt, sources said. The Detroit Tigers were on the fringe of the Oswalt market as of Saturday evening. Other teams were involved, as well.

The Red Sox, who obtained right-handed pitcher Clayton Mortensen for Scutaro, are motivated to upgrade their starting rotation. The cost-cutting Scutaro trade is evidence they must do so while staying within a budget.

Oswalt went 9-10 with a 3.69 ERA in 23 starts and 139 innings with the Philadelphia Phillies last year. The 34-year-old landed on the disabled list twice in 2011 because of back injuries. He has never pitched for an American League franchise.