Joba Chamberlain is about to take the biggest step of his minor league rehab program and move closer to returning to the big leagues.

After throwing one inning for the Yankees' team in the Gulf Coast League Tuesday, the plan calls for Chamberlain to pitch two frames for Single-A Tampa on Friday in Bradenton.

Chamberlain fanned two of the three Phillies' low-level batters he faced, averaged 95 to 96 mph with the fastball and was clocked at 98.