Dan Hooker will stay an extra day in a Milwaukee hospital following his loss to Edson Barboza.
The Kiwi star was beaten by technical knockout in the third round by the UFC's No.5 ranked lightweight yesterday and was transported to hospital for monitoring.
Speaking to ESPN, Hooker's head coach Eugene Bareman said the 28-year-old suffered a concussion in the bout and would be staying in hospital an extra day for observation.
"He was visibly concussed several times, I believe," Bareman said. "We have a very good set of protocols within the gym to take care of him. It's a ruthless game we play. Painful for me to watch that from a distance, but we have been here before many times, so I'm looking forward to the return."
Bareman also confirmed to ESPN Hooker did not suffer any broken bones during the fight.
The bout had many people calling for it to be stopped early, including the commentary team which featured dual weight class champion Daniel Cormier.
Hooker, ranked at No.14, started the bout well and traded shots with Barboza, however the power of Barboza's strikes eventually got the better of the Kiwi - who took a spinning back kick clean to the abdomen which was a turning point in the contest.
He was checked by medical staff at the end of the second round after sustaining a number of powerful strikes, and was judged to be in condition to fight on.
However, midway through the third round Barboza was able to get the stoppage.
"He's a tough guy...one of the best in the world," Barboza said of Hooker when speaking to UFC media after the bout. "He's a tough guy, he's young and he has a good future.
"I really landed good shots, clean with the punches and with the legs but, like I said, I fight with the best guys in the world and he's one of the best. It was a good fight."
The loss was Hooker's first since making the jump up a weight class from featherweight to lightweight and saw his professional record go to 17-8-0.