Sources: Jon Fitch-B.J. Penn fight off
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According to the sources, there has been no replacement named, yet. News of the injury was first reported by MMAWeekly.com.
The two welterweights fought to a draw in the main event of UFC 127 in Sydney, Australia. Two judges scored the fight 28-28 with a third giving Fitch a 29-28 nod. UFC president Dana White later told ESPN.com he scored the bout in Penn's favor.
The result snapped a five-fight win streak for Fitch (23-3-1), dating back to January 2009. The draw sapped some of Penn's momentum from a first-round knockout win over Matt Hughes in November 2010.
Both fighters have already held or fought for the 170-pound title.
Penn (16-7-2) claimed the welterweight belt with an upset submission win over Hughes at UFC 46 in January 2004. Penn vacated the title immediately after but has fought for it twice since, losing to both Hughes and current champion Georges St. Pierre. Fitch fell short in his only attempt, dropping a unanimous decision to St. Pierre at UFC 87 in August 2007.
St. Pierre will look to defend the belt on April 30 against Jake Shields at UFC 129 in Toronto.
Brett Okamoto covers mixed martial arts for ESPN.com.