UFC 270 preview: Why Francis Ngannou v Ciryl Gane is one of UFC's most intriguing heavyweight fights

Francis Ngannou will defend his UFC heavyweight title against undefeated interim champion Ciryl Gane at UFC 270.

Ngannou, 35, is one the most powerful and dominant figures in MMA history, and has won his past five fights via knockout.

Gane, 31, holds a perfect 10-0 record with seven consecutive wins in the UFC, despite only turning professional five years ago.

There's a history between these two fighters. They are old sparring partners, Gane is trained by Ngannou's former head coach Fernand Lopez, and the reigning champion is in the midst of a contract stand-off. Here's your UFC 270 preview for Ngannou v Gane.

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Sparring partners to rivals

Footage of a sparring session three years ago between Ngannou and Gane recently emerged on social media, which showed Gane gaining the upper hand.

Ngannou was hugely annoyed by the leak and hit back by claiming he knocked out Gane during the session at the MMA Factory in Paris.

"First of all, it wasn't sparring footage, it was a clip. I knocked him out with a left high kick," Ngannou said.

Gane would deny this, which resulted in a tense, if friendly verbal exchange between the two at the press conference on Thursday. Gane questioned Ngannou's version of events before calling him a "liar".

Ngannou would go on to relocate permanently to Las Vegas and link up with a new coaching team. Plenty has been said about the split from both sides, but the switch paid off for Ngannou as he became heavyweight champion last March when he knocked out Stipe Miocic.

It was a seemingly impossible dream considering Ngannou's start in life and set the Cameroonian on a collision course with his former team-mate Gane.

Gane becomes interim champion

Gane became the first French fighter to capture a UFC world title when he won the interim heavyweight title at UFC 265 in August.

Interim titles are useful when applied appropriately. Their most common use is when a champion is out for a lengthy period and no title contenders will get an opportunity to fight for the title.

However, Ngannou had only been champion for three months when the UFC announced Gane would fight Derrick Lewis for the interim belt.

The UFC wanted Ngannou to defend his title against Lewis, but the champion said he wouldn't be ready to fight at the proposed time.

Gane would produce a masterclass against Lewis and Ngannou acknowledged 'Bon Gamin' as a "legit contender".

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A 17-second clip surfaced across social media where Ngannou bluntly ignored Gane and his head coach Lopez, which left the interim champion visibly perplexed.

Gane believes Francis was wrong to snub him.

"With Francis, we've never really been that friendly. So, I was a little disappointed because it was wrong," Gane told BBC Sport.

"It was a little strange, but I can understand his point. He was a little bit confused at this moment - he didn't know what to do - he did that [but] it was wrong."

Tyson Fury and contract disputes

Ngannou is unhappy with the UFC because of disagreements over pay and boxing opportunities.

'The Predator' and the UFC have been locked in a contract stand-off for quite some time, with no solution in sight. Ngannou has publicly criticised the promotional company and insisted he wants a new contract to give him the right to compete in boxing. He's set his sights on a fight with boxing world champion Tyson Fury.

Ngannou's title victory was the seventh of an eight-fight contract which means this weekend's fight against Gane will be Ngannou's final UFC bout.

Should Ngannou beat Gane, a champion's clause will come into effect and tie him into one more fight with the UFC. However, if Ngannou loses, he becomes the most sought-after free agent in MMA.

Ngannou has made no secret of his desire to make the switch to boxing one day, but it all hinges on Saturday's result.

"As many of you might know, my dream since I was a kid was to become a boxer. Along the way, I discovered MMA, which has been great to me," Ngannou said.

"But still that hasn't taken away that dream of boxing. I always knew that I wanted to get a part of boxing in my career before the end of my career."

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