Is Rio Ferdinand a fitness concern for Bolton?

The latest tweet from Manchester United defender Rio Ferdinand -- AKA @rioferdy5 -- has prompted concern about the player's fitness for Saturday's upcoming match versus Bolton Wanderers. Here is what the player revealed in that tweet:

When your stomach is making more moves than a gymnast you know its gonna be a long night...it was a long night I must say! Up all night :-(

Quite honestly, this could be nothing other than Rio simply being bored and deciding to share that he has bubble guts with his 1,856,336 followers. Or it could mean that he has some sort of stomach virus just two days prior to United's next match. Either way, United's drastic injury situation through the holidays has trended positive since and manager Sir Alex Ferguson would likely have more cover available if his former captain is unavailable for selection due to illness. Chris Smalling made a surprise return versus Manchester City on Sunday during United's 3-2 FA Cup victory over the holders. In addition, Jonny Evans was a surprise inclusion on the bench. Both of them could be options to feature at center-back versus Bolton as could Phil Jones. Midfielder Michael Carrick is an option as well.

We will have full coverage of Fergie's weekly press-conference tomorrow as he likely will provide the latest in regards to the injuries and illnesses in his squad.