Former lightweight champion Sean Sherk (33-4-1) has been forced to turn down a potential barnburner against Clay Guida at the upcoming UFC on Versus event from The Odeum Colorado after lingering injuries hampered his preparations for the March 21 event.

"The Carpenter" is expected to remain on the card against an opponent to be named.

This is the third straight event the "Muscle Shark" has been forced to withdraw from. In fact, Sherk hasn't competed since a unanimous decision loss to Frankie Edgar at UFC 98: "Evans vs. Machida" in a battle of the mitts back in May 2009.

He was booked for a 155-pound scrap opposite Gleison Tibau at UFC 104: "Machida vs. Shogun" last October; however, a "Grade II AC separation" in his right shoulder nixed the contest and allowed Josh Neer to take his place.

Sherk was then re-booked to battle fellow wrestler Jim Miller at UFC 108: "Evans vs. Silva" after a whirlwind of fight card changes. Unfortunately that didn't last either, as a severe forehead laceration put the kibosh on his Jan. 2 return.

The former welterweight has come under fire for his rash of training injuries that have plagued him in the latter part of his career following a positive steroid test on the heels of his win over Hermes Franca at UFC 73: "Stacked" in July 2007.

The test itself was administered during a very shady time in the much-maligned California State Athletic Commission's (CSAC) history and Sherk continues to maintain his innocence, yet the court of public opinion has been (perhaps unfairly) unforgiving on the Minnesotan.

Sherk has also been criticized for abandoning his roots (wrestling) which was a big factor is his divisional dominance for so many years in favor of a new stand-up attack that favored him in a UFC 90 bout against Tyson Griffin but cost him the aforementioned fight against Frankie Edgar.

At the ripe old age of 36, the "Muscle Shark" needs to dial it in sooner rather than later if he wants to head back toward title contention before calling it quits.

Assuming he can stay healthy long enough to get back inside the Octagon.