The UFC Fight Night co-main event between Jeremy Stephens and Drakkar Klose in Las Vegas was cancelled on Saturday due to a weigh-in push.
Klose says he sustained injuries following opponent Stephens' push on him during Friday's weigh-in.
The 33-year-old said he felt his hand go numb and his neck tighten up immediately after being forcefully shoved on stage during the ceremonial face-off and woke up with a headache and nausea on Saturday morning before checking into a hospital.
Klose's CT scan results revealed he had suffered a cervical sprain of the neck and concussion, although UFC said the lightweight bout was off without providing details of Klose's injury during their broadcast.
"I'm sorry to everyone who was excited for this fight," Klose said in a tweet. "I tried to do everything I could to stay in this fight but these issues are out of my control."
Stephens said in an Instagram post that he pushed Klose for getting too close to him "with aggressive behaviour" during the weigh-in.
"I just have zero tolerance for that type of disrespect," he said.
Klose most recently fought in March 2020 at UFC 248, where he suffered a knockout loss to Beneil Dariush but has won three of his last four bouts.
Meanwhile, Stephens was set to return to the lightweight division after a seven-year stint as a featherweight and is winless in his past five fights.
The other headline UFC Fight Night bout in Las Vegas went ahead as planned with Robert Whittaker cruising to a unanimous decision against Kelvin Gastelum.
Whittaker stunned Gastelum in the first round en route to 50-45 wins across all cards in their UFC middleweight fight.
The Australian-New Zealand fighter more than doubled Gastelum in total strikes, recorded four takedowns of the American and dominated control of the fight, over four minutes to just 26 seconds for Gastelum.
Whitaker now has his sights set on a rematch with middleweight champion Israel Adesanya, who defeated Whittaker with a second-round TKO on October 2019 at UFC 243.
"I think we should talk, mate," Whittaker said afterwards. "I think it's about time we crossed paths once again. I think I have some tricks he hasn't seen yet."
Earlier, Andrei Arlovski won a unanimous decision over Chase Sherman in their heavyweight bout.
It was a tightly-contested fight but Arlovski scored a 29-28 decision across all cards. Arlovski, 42, made his UFC debut in 2000 and is third all-time in appearances (35).
Meanwhile, Jacob Malkoun recorded a unanimous decision over Abdul Razak Alhassan in their middleweight contest, taking all three cards 30-27.
Tracy Cortez defeated Justine Kish in a split decision in their women's flyweight bout with Cortez taking two cards 29-28 and 30-27, while Kish took one card 29-28.
Luis Pena also won a split decision over Alexander Munoz in their lightweight bout. Pena was the 29-28 winner on two cards but dropped one card by the same score.