Roy Nelson (15-4 MMA, 2-0 UFC) won't be tussling with Cheick Kongo after all.

Kongo (15-6-1 MMA, 8-4 UFC) has withdrawn from a rumored meeting with Nelson at UFC 116 due to a back injury, according to multiple reports. In his place, the UFC has slotted a surprising replacement: Junior Dos Santos (11-1 MMA, 5-0 UFC).

According to MMAjunkie.com (www.mmajunkie.com) sources close to the event, at least one fighter has agreed to the contest, now targeted for the main card of UFC 117, with the intention to sign a bout agreement.

UFC 117 takes place Aug. 7 at Oracle Arena in Oakland, Calif. A middleweight title match between champion Anderson Silva and challenger Chael Sonnen is expected to headline.

Nelson, 33, racked up his second consecutive octagon victory with a shellacking of 6-foot-11 Stefan Struve at UFC Fight Night 21 in March. The winner of "The Ultimate Fighter 10" bucked most predictions by quickly getting inside on Struve and knocking him out with a right hand in just 33 seconds.

Previously, Nelson completed a decisive, yet controversial, sweep of the "TUF 10" heavyweights with a first-round knockout of Brendan Schaub in the show's finale. UFC president Dana White criticized his tactical approach to his fights on the show, and despite some initial push-back with the outspoken UFC figurehead, he later told MMAjunkie.com that he is now a "company man."

The 25-year-old Dos Santos fought at UFC on Versus 1 and delivered his fifth consecutive stoppage victory when he knocked out former contender Gabriel Gonzaga in less than four minutes. The victory put the up-and-comer on many observers' lists as a serious contender in the division, which could make the fight with Nelson all the more pivotal.

The only man to make it out of the first round with Dos Santos is former PRIDE champion Mirko "Cro Cop" Filipovic, who verbally submitted to the Brazilian in the third round after being battered for more than two rounds.

Dos Santos also owns a first-round knockout victory over Struve, which took place at UFC 95 this past February.