Not only did Alistair Overeem knockout Mark Hunt in brutal fashion at UFC 209, but he did so while battling a case of food poisoning.

Overeem, who rebounded from his KO loss to Stipe Miocic with a third round knockout of ‘Super Samoan’, was in the hospital for 24 hours in the lead-up to Saturday night’s pay-per-view.

That’s according to UFC president Dana White, who told reporters at the post-fight press conference that ‘The Reem’ was seriously ill.

“Did you know that he was sick,” White said at Las Vegas’ T-Mobile Arena (h/t Chuck Mindenhall of MMA Fighting). “So, he’s been in the hospital for 24 hours. Food poisoning. Throwing up and all the other pleasantries of food poisoning for 24 hours. He was in the hospital, brought him home, and we had to bring him back to the hospital. They had to fill him with bags of fluids, and IVs, and at one point he was afraid to leave his room because he couldn’t stop throwing up and everything else.”

The heavyweight veteran rendered Hunt unconscious with two devastating knees in the clinch, dropping his opponent face first onto the mat and scoring one of the best knockouts of his UFC career.

Overeem wasn’t going to mention his illness at the post-fight conference, but White insisted on telling the media.

“[He] did not want to turn down the fight. [He] still came out and fought tonight and knocked out Mark Hunt. So, and more to his credit, didn’t say one word about it in his interview, and obviously hasn’t said it here yet. I just came in to thank him and tell him how much I respect him.”

The former K-1 world champion elaborated on his condition, revealing that he was sick at the weigh-ins and was permitted to use an IV at the hospital.

“So, we went through all the steps necessary,” Overeem explained. “I got really sick. Yesterday at the weigh-ins I was out. I was like low energy. I mean, I put on my acting face looking angry, but I had zero energy, and if i felt today as I did yesterday I would not have been able to perform. But, I went to the hospital, got an IV, slept very good, took something to help me sleep. I could get some food in yesterday even before sleeping and recovered kind of okay, and [thought] yeah, we’re going to go for it. We’re going to do this.”

Despite losing to Miocic via KO in September, Overeem looked in top form against Hunt. The 36-year-old out-struck Hunt in the opening rounds and finished him with an exclamation point in the third.

Overeem is currently ranked at No. 3 in the official UFC heavyweight rankings and has won five of his last six fights.