Fans recoil as headbutted UFC star shows off gruesome cut (GRAPHIC VIDEO)

Ex-UFC champ Carla Esparza's proposed world title fight against Rose Namajunas may be in jeopardy after she suffered a massive gash above her right eye following a clash of heads with her opponent in a grappling match.

The 34-year-old, who was the UFC's first-ever strawweight champion, has been heavily linked to a forthcoming fight with reigning champ Namajunas after piecing together a five-fight, two-and-a-half year long unbeaten streak in the UFC's 115lbs fold.

Those plans, along with her eyebrow, may have to be put on ice following the shocking clash of heads with Danielle Kelly at Fury Pro Grappling 3 in Pennsylvania on Thursday night.

Warning: video contains graphic content

Esparza, who somewhat ironically had replaced Namajunas in the match after the UFC queen bowed out, was in top position when she attempted to slam her opponent to the mat – succeeding only in engineering the clash of heads with Kelly, which quickly caused blood to flow.

The referee first paused the action and then called off the match due to the advice of a doctor after it was determined that the cut was too big for the contest to safely proceed.

Kelly later addressed the incident on social media, writing: "I just want to say I wish [Esparza] a speedy recovery.

"Not me or her were expecting that and maybe [there will be] a rematch in the future if it doesn’t get between schedules.

"Honestly, I was confused and a lot of adrenaline was going through me. I was just really excited to be a part of a huge event with everyone watching. I'm also just nerding out this mark on my face."

Esparza, meanwhile, posted a gruesome close-up of the cut which appears to be around an inch in length, and said that it was going to require "a couple of stitches".

"Sorry guys, accidental headbutt on a slam led to a cut and a stop in the match," she wrote. "In good spirits. Just gotta get a couple stitches."

It is unclear how long Esparza will need on the sidelines for the wound to fully heal, but it seems certain to derail a proposed title shot against Namajunas, which insiders had suggested was being talked about for early 2022.

Twitter users were quick to point out how potentially costly the cut might end up being for Esparza.

One suggested that the injury might be all that is required for Dana White to book what would be a third world title fight between Namajunas and her Chinese rival Zhang Weili, while another said that Esparza shouldn't have been quite so careless on the mat.

"I don’t even feel bad. That’s what people get for slamming in jiu-jitsu," they wrote.

"Almost never does it work out for the person who is doing the slamming – even in MMA," they wrote.

A third, though, had a slightly different reaction, responding: "Eww – you can see the meat inside."