BOSTON -- The Red Sox confirmed that highly touted prospect Will Middlebrooks will miss the remainder of the Arizona Fall League after spraining his left thumb on Tuesday.

"They cast it just to allow the thumb to be stable and heal," said Red Sox general manager Ben Cherington. "It sounded like about a four-to-six-week recovery. He'll miss the [Rising Stars Game], but it shouldn't get in the way of his offseason."

A third baseman, Middlebroks is considered by many to be one of the best hitting prospects in the organization.

Middlebrooks played 13 games in the AFL for Scottsdale, hitting .250 with four homers and 11 RBIs. Middlebrooks spent most of 2011 playing for Double-A Portland, but got a late-season promotion to Triple-A Pawtucket. His combined numbers for the season included a .285 average with 23 homers and 94 RBIs.

Another top Sox prospect -- catcher Ryan Lavarnway -- has returned home from the Venezuelan Winter League to tend to a personal issue. He won't return to Venezuela.

In five games, Lavarnway hit .357 with no home runs or RBIs.