Phil Mickelson using long putter

NORTON, Mass. -- Phil Mickelson won 39 PGA Tour titles -- four of them major championships -- with a blade-style putter.

But Friday afternoon, he began his first round of the Deutsche Bank Championship with a belly putter -- a 45-inch Odyssey Sabertooth with a White Hot XG insert.

Earlier this week, Mickelson was at the Odyssey Putting Lab in Carlsbad, Calif., to iron out the specifics of his new putter, which is similar to the one PGA Championship winner Keegan Bradley uses. Mickelson's model is a half-inch shorter and is two degrees more upright than Bradley's.

In 2011, six players have won PGA Tour events using long or belly putters, including Bradley, who won twice with his Odyssey Long putter.

Bradley, a 25-year-old rookie, has mentored the 41-year-old Mickelson about the merits and intricacies of the long putter.

"I think that any way Phil putts, he'd make anything," Bradley said after shooting 68 on Friday in the first round at TPC Boston, "but it's really an honor to have Phil talk to me about anything in terms of the game."

Farrell Evans covers golf for ESPN and can be contacted at evans.espn@gmail.com