Khabib Nurmagomedov has admitted he allowed his heart to rule his head during his win over Conor McGregor.
The UFC lightweight champion was involved in a bitter feud with his Irish rival before they fought in 2018.
And when the cage door was locked, Nurmagomedov admits he deviated from his usual tactics and tried to hurt McGregor.
The 32-year-old, who won by fourth-round submission, said: "I don’t like to give people damage. Just finish them, make them sleep.
"I tried to hurt this guy [McGregor] and it was my mistake. When you become angry, you’re tired. When I try to give him, like, punish... it was very emotional.
“Then, I think, 'OK, no, no, no. I’m going to become calm now'."
Nurmagomedov went on to defend his title on two further occasions, against Dustin Poirier - who takes on McGregor this weekend - and Justin Gaethje.
He announced his retirement following his victory over Gaethje last October but retains his 155lb title.
He held talks with UFC president Dana White last week over a potential return but remains non-commital.
McGregor, meanwhile, insists he will move on from the defeat if he is not granted the opportunity for revenge.
He said: "It's a tough business, things have gone on in his personal life, I don't wish any harm, it was 2018, a lot of time has passed.
"The world knows this war is not over, the sport needs it to happen, the people need it to happen.
"I'm not going to chase it if he doesn't want it. I'll keep my calm and move on.
"That's what I'm doing, I'm back here at the 155lb division, I'll show the world what's what over time and that's it. It begins on Saturday night against Dustin Poirier."
Since losing to Nurmagomedov, McGregor has fought just once - a 40-second demolition of Donald Cerrone 12 months ago.
Victory over Poirier on Sunday morning will propel him into pole position for a lightweight title shot - either against Nurmagomedov or for the vacant belt.
