Lightweight champion Khabib Nurmagomedov announced his retirement following his second-round win over Justin Gaethje at UFC 254 on Saturday.
Khabib's father and head coach Abdulmanap Nurmagomedov died in July because of complications with the coronavirus, and the Russian champion said his father's death played a role in his decision to leave the sport.
"This was my last fight," Khabib said. "No way am I going to come here without my father. ... I promised [my mother] it will be my last fight. If I give my word, I have to follow this."
Coming into Saturday's event, Gaethje was the interim lightweight champion after his knockout of Ferguson in UFC 249.