UFC on ESPN 16: Holly Holm vs. Irene Aldana Full fight
A women's bantamweight bout between former UFC Women's Bantamweight Champion Holly Holm and Irene Aldana served as the event headliner. The pairing was originally scheduled to headline UFC Fight Night: Brunson vs. Shahbazyan. However, it was reported on July 22 that Aldana pulled out of the fight due to testing positive for COVID-19. Holm was also removed from the card as well, with the pairing left intact and ultimately rescheduled for this event.
A UFC Middleweight Championship bout between current champion Israel Adesanya and Paulo Costa served as the event headliner. The bout was originally targeted for UFC 248, but Costa was unable to compete on that card due to injury. In turn, Adesanya defended his title against former title challenger (as well as 2000 Olympic silver medalist and former world champion in freestyle wrestling) Yoel Romero.
A UFC Lightweight Championship unification bout between current champion Khabib Nurmagomedov and interim champion Justin Gaethje (also former WSOF Lightweight Champion) served as the event headliner.The bout was briefly linked to UFC 253, but the date did not materialize and instead took place five weeks later. On September 17, the UFC announced the signing of former three-time Bellator Lightweight World Champion Michael Chandler, who served as backup and a potential replacement for this fight
A UFC Light Heavyweight Championship bout for the vacant title between former title challenger Dominick Reyes and former KSW Light Heavyweight Champion Jan Błachowicz. Former two-time champion Jon Jones vacated the belt on August 17, citing issues with the UFC over salary negotiation and the desire to compete at heavyweight.