Derek Brunson has been forced out of UFC 200 due to a problem with his vision, so Brazilian striker Thiago Santos has stepped up to face Gegard Mousasi on the card taking place on July 9 in Las Vegas.

UFC officials confirmed the new matchup Monday.

Brunson explained that he has experienced blurriness and double vision for the past two weeks and that he'll need work done on his eyes after initially having Lasik surgery four years ago.

With Brunson out, the UFC turned to Santos as a replacement, who enters UFC 200 on a four-fight winning streak inside the Octagon.

Most recently, Santos dispatched former title contender Nate Marquardt by first-round knockout to notch his third finish by strikes in his past four fights.

Santos now faces Mousasi, who is coming off a win in his last fight over Thales Leites in February.

The new bout between Santos and Mousasi is expected to join the preliminary card at UFC 200, which will take place at the new T-Mobile Arena in Las Vegas with three title fights as well as the return of Brock Lesnar.