If Greg Whittington's return from academic ineligiblity is a big reason Georgetown isn't expected to take a big step backward without Otto Porter, then it may soon be time to revise those predictions.

Whittington suffered a "significant" knee injury severe enough to jeopardize his season, ESPN.com reported Tuesday. The extent of the injury is unclear at this time because the school has yet to confirm it, but CasualHoya.com reported Whittington has been seen on campus on crutches and cited a source who said Georgetown fears the 6-foot-8 forward has suffered a torn ACL.

If Whittington's injury is indeed season-ending, that's a major blow to a Georgetown team with aspirations of winning the new Big East next season. Whittington averaged 12.1 points and 7.0 rebounds before being ruled academically ineligible last January prior to a game against St. John's.

The challenge of replacing Porter's 16.5 points and 7.2 rebounds per game becomes much more difficult for Georgetown if Whittington is unavailable.

Rising senior Nate Lubick and rising junior Mikael Hopkins both return, but neither has proven they can be a consistent interior scoring threat. Highly touted freshman Reggie Cameron could play some power forward in a pinch, while UCLA transfer Joshua Smith is capable of making a huge impact at center once he becomes eligible in mid-December but only if the massive 7-footer can trim 30 or 40 pounds.

Throw in guards Markel Starks and D'Vauntes Smith-Rivera, and there's still more than enough talent on the Georgetown roster even without Whittington to return to the NCAA tournament and even contend in the new Big East. Still, you can't blame Georgetown fans for hoping that Whittington's injury turns out to be less severe than currently feared.

Related coverage on Yahoo! Sports:
• Johnny Manziel tweets he wants out of A&M
• Trevor Lacey's transfer should boost North Carolina State
• Little-known Elfrid Payton emerges at U-19 basketball tryouts