An MRI confirmed Thursday that Braves outfielder Matt Diaz has a partial tear in the posterior cruciate ligament of his left knee, and he is out four to six weeks.

Surgery is not required. Doctors think it's a matter of rest and rehabilitation and fitted Diaz for a brace.

Diaz injured his knee Tuesday night, crashing into an outfield wall knee-first trying to catch a Prince Fielder foul ball. Diaz returned to Atlanta from the road trip Wednesday, when he was placed on the disabled list, and had the MRI on Thursday.

Diaz had struggled at the plate lately, but he broke an 0-for-12 stretch Tuesday with a single. He had been counted on as a platoon player in left field. The Braves played Omar Infante in left field Wednesday, and Greg Norton is in the lineup today.

Mark Kotsay is still out with back stiffness, so the other half of the platoon in left field — Gregor Blanco — has been playing center.