Thiago Santos will headline his first UFC event next month, and he’s a little surprised it’s actually happening.

In his light heavyweight debut, the Brazilian is set to face Jimi Manuwa in the UFC Sao Paulo main event on Sept. 22. The former middleweight is moving up a weight class on short notice for the injured Glover Teixeira.

At first, however, it seemed that Manuwa was uninterested in the Santos bout on short notice. The British fighter ended up agreeing to it, but that’s not what “Marreta” was expecting.

“I thought he wasn’t going to accept it, considering I’m not in the division,” Santos told MMAjunkie. “He’s a top-five (fighter), so it’s tricky to take on a guy who’s not even in the division. Not everyone would have taken it. I’d have understood it, for sure (if he turned it down).”

Headlining a UFC event has been on Santos’ bucket list for a while, and he nearly had the opportunity to do so last year. He was briefly linked to the UFC Gdansk main event against newcomer Michal Materla, but Materla ended up not signing with the UFC, and Santos did not fight on that card at all.

Coming off a unanimous decision win over Kevin Holland at UFC 227 earlier this month, Santos believes this is the perfect time to headline his first card, considering it’s taking place at 205 pounds.

“I’ve waited so long for an opportunity to be a main event,” Santos said. “I almost was once, but the guy didn’t take it, he left the UFC, didn’t sign the contract, that whole thing happened. So it ended up not happening.

“I’ve been waiting for this for so long. It wasn’t in my division, but I’ve been wanting to try my hand at light heavyweight. So the two things came together, and I’m very happy with this opportunity.”

Santos isn’t exactly sure what to expect at the new weight class. Manuwa is a top 10 light heavyweight, so a win over him would be huge for Santos, but he’s currently unsure — for several reasons — if he’ll stay at light heavyweight after the bout win or lose.

“I’d already talked to the UFC about doing a fight at light heavyweight to see how I would feel,” Santos said. “Because though I always make weight, I suffer a lot to make 185 pounds. So I wanted to do a fight at 205 to see how I’d feel. I’ve never fought there, so I have to weigh the pros and cons. Maybe I’ll be stronger, but I might also be slower. There are many variables. Maybe the guy will be much stronger than I am. We don’t know. So I wanted this fight already. This opportunity came – we’ll do it.

“But there’s nothing definitive on whether I will continue or if I’ll return to middleweight. Whether I win or I lose, that’s not what will determine whether I stay or not at light heavyweight. What will determine that is how I’ll feel, making 205 in one day and fighting the next. I’ve never done that. I’ve never fought anyone heavier than me, so we’ll see how I will feel.”