Israel Adesanya brought in a private doctor without telling UFC officials, just days before Sunday's big fight with Anderson Silva, after he spent most of the week with a sore throat.
The Nigeran born Kiwi claimed his biggest scalp in his mixed martial arts career so far, beating Silva in Melbourne on Sunday at UFC 234.
His coach, Eugene Bareman, told 1 NEWS today that before Adesanya boarded his flight to Melbourne last week he had a mild sore throat, but it had worsened once he landed in Australia.
"His neck had swollen up and some of his lymph nodes were swollen," he explained. "It was a big concern because his energy started to drop as well."
Otherwise known as the "Stylebender", Adesanya was prescribed penicillin to relieve what was thought to be glandular fever or tonsillitis.
"We brought a private doctor in," his coach said. "We wanted to hide it from the UFC because we are not going to pull out of the fight no matter what.
"When he hopped off the plane, it had worsened quite a bit and over the day and especially the next day he almost couldn't talk," Bareman added.
Fortunately for Adesanya, he overcame the illness just days before the biggest fight of his career
His coach described all three of the Kiwi fighters' wins in the UFC 234 event as a big moment for the Auckland City Kickboxing gym.
"I feel relief," Bareman explained. "Relief is the first feeling I have, and as each fight progressed and we got the desired result I definitely felt a little bit of weight come off my shoulders.
"We talked about it - all three of us winning, getting the W - and we focused in on that intensity for eight to 12 weeks. As each of those wins came, more and more weight removed off my shoulders. That was amazing."
Kiwi featherweight fighter Shane Young won his bout via unanimous decision while his City Kickboxing teammate Kai Kara France won his flyweight fight via split decision.