Jeremy Stephens and Drakkar Klose’s UFC Fight Night co-main event was called off on Saturday after Klose said he suffered a neck injury when he was pushed by Stephens during the weigh-in.
The American said he felt his “hand go numb and neck tighten up” after the push on Friday, and woke up the next day with a headache and nausea.
He is reported to have been diagnosed with a neck sprain and a concussion.
“I’m sorry to everyone who was excited for this fight,” Klose said on Twitter.
“I tried to do everything I could to stay in this fight, but these issues are out of my control.”
Fellow American lightweight Stephens said Klose had got “just got a little too close with aggressive behaviour” during the weigh-in.
“I just have zero tolerance for that type of disrespect,” he added.
In the middleweight main event in Las Vegas, Robert Whittaker dominated Kelvin Gastelum to win via unanimous decision.
Whittaker overwhelmed Gastelum in all five rounds, landing more than double the American’s total strikes as he took 50-45 wins across the cards.
The New Zealand-born Australian fighter now wants a rematch with middleweight champion Israel Adesanya, who beat him with a second-round technical knockout in October 2019.
“I think it’s about time we crossed paths once again,” Whittaker said. “I think I have some tricks he hasn’t seen yet.”
Earlier on the main card, Andrei Arlovski won via a tight unanimous decision against Chase Sherman in their heavyweight bout, while Jacob Malkoun took all three cards 30-27 in a unanimous decision win over Abdul Razak Alhassan at middleweight.
Luis Pena beat Alexander Munoz in a split decision in their flyweight fight, and Tracy Cortez also won via split decision over Justine Kish at women’s flyweight.