The main event at UFC Vegas 91 features a flyweight contest between the No.5-ranked Matheus Nicolau and the No.8-ranked Alex Perez.In April 2023, Nicolau (19-3-1) suffered the first loss in his second stint with the UFC via first-round KO to Brandon Royval. Prior to that, he was on a four-fight win streak in the promotion.This weekend, the Brazilian will be hoping to get back to winning ways and reaffirm his place in the divisional top five with a dominant win.The other half of the main event, Perez's (24-8) career has been on a downtrend in recent years. He is on a three-fight skid with his most recent loss coming via unanimous decision to Muhammad Mokaev in March.With his last win having come in 2020 at UFC 250, the 32-year-old is in dire need of a win to revive his career.Per the UFC's website, Nicolau is a -175 favorite over Perez (+145 underdog).Catch the live results and play-by-play updates on Sportskeeda MMA as the main event unfolds at UFC Vegas 91.Watch Matheus Nicolau face off against Alex Perez below: View this post on Instagram Instagram PostUFC Vegas 91: Matheus Nicolau vs. Alex PerezRound 1:Both men are exercising caution in the opening moments of the fight. Nicolau is opening up with quick jabs. Perez answers with a leg kick. Perez connects with a long flurry both upstairs and to the body.Nicolau misses with a left hook. Perez connects with a body shot and follows up with an uppercut to the head. Nicolau counters his opponent with a left hook, seemingly stunning Perez.A very close round.Round 2:Perez comes out aggressively connecting with another flurry, finishing with an inside uppercut to the head. The American is pushing the pace denying Nicolau a chance to mount an effective offense. Another flurry lands for Perez.Nicolau gets stunned by a lead right hook by Perez. Perez forces his foe to the cage with a flurry and catches his opponent at the end of a right hook putting his lights out. That's a wrap, folks.Official Result: Alex Perez def. Matheus Nicolau via KO (2:16 of Round 2)Watch Alex Perez's KO over Matheus Nicolau at UFC Vegas 91 below: