BOSTON -- For the first time since May 5, Aaron Cook will start for the Red Sox.

After recovering from a gash on his leg that required 11 stitches, the 33-year-old was purposely scratched from Saturday's start in Pawtucket to start in Sunday's game against Atlanta in place of Clay Buchholz, who is battling an undisclosed illness.

When Cook takes the mound at Fenway Park, expect a few deviations from his traditional sinkerball. Under pitching coach Bob McClure's watch, Cook incorporated a new pitch to his arsenal -- a cutter.

"With the arm strength he's got now, it looks like he may be able to throw one," McClure said. "It's a really nice pitch for a sinkerballer to have because they nullify left-handed hitters. It's enough to keep left-handed hitters honest it's moving the opposite way, it's hard. I think it could be a good pitch for him."

Shortly after Cook suffered his leg injury, the idea was born. As he played catch with McClure one day -- because he was limited due to injury -- the Red Sox pitching coach asked Cook if he'd ever experimented with a cutter.

Cook attempted to showcase one, but McClure was far from pleased, calling the endeavor "some sort of slider." Despite initially failing, Cook remained interested in developing a cutter to complement his sinkerball.

So he started peppering Red Sox starter Josh Beckett with questions about grips with cutters. Before long, Cook formed a grip similar to Beckett and started turning heads in bullpen sessions with McClure.

"I know this -- he threw some in Toronto [in the first weekend of June] that were really good," McClure said. "You don't want to try to jam the guy. If it's low, the left-handed hitters can get to it too easy. Once you start elevating it high thigh to above the belt it's really good and he threw some really good ones."

It won't supplant his sinkerball as a primary pitch, by any means. But during his seven weeks on the shelf, Cook was hell-bent on improving his chances of returning to the Red Sox' rotation.

In order to achieve that goal, the hurler realized he needed to become more versatile with his pitches.

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