UFC Welterweight Champion Georges St. Pierre (13-1) sustained a knee injury training for his upcoming bout with Matt Serra (7-4) and won't be ready for the February 3 fight, according to UFC.com.

Here's a snip:

UFC Welterweight Champion Georges St. Pierre has been forced to withdraw from February 3rd's UFC 67 card due to a knee injury suffered during training for his first title defense against Matt Serra.

This is bad, bad news.

Here's what GSP's trainer, Stephane Patry, told MMAWeekly.com:

"Georges went down to New Mexico to help Keith Jardine, Rashad Evans, and Nate Marquardt to prepare for their fights, returning a favor. [The Greg Jackson-trained fighters had helped St. Pierre prepare for his fight with Matt Hughes.] They were doing some wrestling drills and he slipped on some sweat and hurt his knee. He was still going to be able to fight, but it got worse when he came back to train in Montreal."

According to the interview, St. Pierre went to a specialist and had the knee examined at which time it was determined he sprained his MCL and PCL — there was no damage to his ACL.

Here's what Patry had to say on the prognosis:

"... the injury is not career threatening. The doctor recommended Georges take four weeks off for the injury to heal before returning to training...."

This is not the first time that GSP has hurt himself getting ready for a fight. Prior to his rematch with Matt Hughes last year, "Rush" pulled his groin and had to postpone the highly anticipated — and highly marketed — pay per view (PPV) event.

Fortunately, BJ Penn was waiting in the wings to fill his spot.

This time around, however, it's not as big a fight. And the card is still packed with all-star talent such as Anderson Silva, Mirko "Cro Cop" Filipovic and Quinton "Rampage" Jackson.

Regardless, this entire situation is still very disappointing -- injuries are just a part of the sport.

There's been no indication whether or not Serra will remain on the UFC 67 fight card or wait until St. Pierre is healed.

It is likely that St. Pierre will return at UFC 69 on April 7 in Houston, Texas.