UFC on ESPN: Holm vs. Aldana (also known as UFC on ESPN 16 and UFC Fight Island 4) was a mixed martial arts event produced by the Ultimate Fighting Championship that took place on October 4, 2020 at the du Forum on Yas Island, Abu Dhabi, United Arab Emirates. Background Without fans in attendance, the promotion did not have to worry about the local timing of the event, so the plan was to proceed with normal timing for prime time hours on the east coast of North America. The main card was scheduled to begin at 6:30 am (October 4) local time in Abu Dhabi, with a full preliminary card beginning at approximately 3:30 am Gulf Standard Time. 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 had 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. Ben Sosoli was briefly linked to a heavyweight bout with Yorgan de Castro. However, Sosoli pulled out of the fight in late July citing an eye surgery and was replaced by Carlos Felipe. A women's bantamweight bout between former UFC Women's Flyweight Champion Nicco Montaño and Julia Avila was originally scheduled for UFC Fight Night: Lewis vs. Oleinik. However, due to Montaño’s coach John Wood testing positive for COVID-19, the bout was rescheduled for UFC Fight Night: Overeem vs. Sakai. In turn, it was announced on August 29 that Montaño herself tested positive for the disease and the bout was once again pushed back to this event. On September 3, it was announced that Montaño withdrew from the bout due to travel restrictions. In turn, Avila was rescheduled to face Sijara Eubanks at UFC Fight Night: Waterson vs. Hill on September 12. A light heavyweight bout between former UFC Light Heavyweight Championship challengers Thiago Santos and Glover Teixeira was initially scheduled to headline UFC Fight Night: Waterson vs. Hill. However, the pairing was rescheduled for this event after Teixeira tested positive for COVID-19 a week prior to the fight. On September 15, the bout was postponed again as Santos tested positive for the disease. Charles Oliveira was expected