Thiago Alves will have to sit on the sidelines again following a knee injury.

Alves (20-9 MMA, 12-6 UFC) was scheduled to face Jordan Mein (28-9 MMA, 2-1 UFC) in the co-headliner of UFC Fight Night 49, which takes place Aug. 23 at BOK Center in Tulsa, Okla. Now, prospect Brandon Thatch (11-1 MMA, 2-0 UFC) takes the booking, officials announced today.

The event’s main card airs live on FOX Sports 1 after prelims on UFC Fight Pass.

Alves’ injury won’t necessitate surgery, but will keep him from competing on the summer card, a representative from American Top Team told MMAjunkie. The rep asked for anonymity because he wasn’t allowed to discuss the matter.

It’s yet another setback for the onetime title challenger, who in April returned from a two-year injury layoff to earn a decision over Seth Baczynski at UFC on FOX 11.

Since a loss to now-former champ Georges St-Pierre in 2009, Alves has hopscotched between wins and losses.

Thatch, meanwhile, gets another opportunity to build his name. The former RFA fighter picked up his second straight UFC win with a first-round TKO of Paulo Thiago at UFC Fight Night 32. In his octagon debut, he TKOd Justin Edwards in the first round at UFC Fight Night 27.

Thatch’s only setback in 12 pro fights is a decision loss to Brandon Magana under the now-defunct Strikeforce banner in 2008.

For more on UFC Fight Night 49, check out the UFC Rumors section of the site.

(Pictured: Thiago Alves)