Khamzat Chimaev Misses Weight for UFC 279 Main Event Fight vs. Nate Diaz

Khamzat Chimaev missed weight Friday ahead of his UFC 279 fight against Nate Diaz on Saturday night in Las Vegas.

UFC noted that Chimaev weighed in at 178.5 pounds and would be given an additional hour to lose 7.5 pounds in order to get under the welterweight limit:

Ariel Helwani of BT Sport reported that Chimaev missed weight because of a "medical issue," although specifics are unknown.

Nolan King of USA Today reported earlier in the day that UFC was expecting Chimaev to miss weight and had formulated a backup plan in case it happened.

Alternative options for UFC include holding the fight at catchweight, finding a replacement opponent for Diaz or canceling the fight completely, which would be far from ideal one day before the event.

Chimaev vs. Diaz was already marred by controversy entering the weigh-in due to issues that forced the cancellation of a press conference on Thursday.

Per ESPN's Marc Raimondi, multiple fighters and their teams got into an altercation backstage at the press conference, and UFC president Dana White later said it was started by Chimaev and Kevin Holland, calling it a "complete s--tshow."

The 28-year-old Chimaev is one of the fastest-rising stars in MMA, as he owns a perfect 11-0 record with six knockouts and four submissions.

Most recently, he beat Gilbert Burns by unanimous decision at UFC 273 in April in what was the highest-profile fight of his career.

Chimaev is looking to step up against arguably an even tougher opponent in Diaz, who has faced many of the biggest names in UFC during his career.

Diaz, 37, is 20-13 as a professional with wins over the likes of Conor McGregor, Anthony Pettis and Donald "Cowboy" Cerrone.

While Diaz has lost three of his past four bouts, he is still a dangerous fighter capable of threatening Chimaev's undefeated mark.

With Chimaev failing to make weight, however, the main event of UFC 279 is very much in question.