St-Pierre sensationally vacated the welterweight belt he had held for seven years and stepped away from the sport in 2013 after winning a controversial split decision over Johny Hendricks in a fight that 16 media organisations scored for Hendricks.

However St-Pierre, considered the greatest welterweight in history and perhaps the truest embodiment of a mixed martial artist, continued to train during his self-imposed sabbatical.

UFC president Dana White announced on Thursday morning that GSP was officially back, and would face reigning champion Michael Bisping for the middleweight title at a yet-to-be determined point in 2017, despite St-Pierre having never fought at middleweight.

Evans will make his middleweight debut this weekend at UFC 209 against Melbourne fighter Dan Kelly after suffering back to back losses for just the second time in his 13-year MMA career.

A long-time MMA analyst for ESPN, Evans said that the Bisping-St-Pierre fight had many intangibles in play especially given that GSP has never fought at middleweight before.

He admitted that while GSP is probably the superior fighter, Bisping has a habit of making even the best look, well, average.

"You take GSP, who hasn't fought since 2013, and you put him in a position where he's fighting for a title ??? when you're out of the cage the sport changes so fast, you're not stepping into the same Octagon in which you left," Evans said.

"Even though he's been training - I've seen him, he's been training harder than he was, or just as hard as when he was training for a fight - but training is training and a fight is a fight.

"Not being tested inside the octagon can play against him.

"Then you have Michael Bisping, who always finds a way to get it done.

"He's one of those guys who finds a way to make the best guy maybe not look so good.

"You look at his skill level and you think he's not the most skilled but for whatever reason, he finds a way to make everyone march to his beat in some sense.

"You look at the fact that GSP is, I think, technically better than him in almost every area, you kinda have to go for GSP but it's a pick 'em, I'm going to need to look at the training camp for both guys before I can make an educated call on that one."

Like GSP, Evans will make his middleweight debut in his fight against Kelly and while trash-talk seems to be the flavour of the day in the UFC, Evans - who certainly knows how to talk, as anyone who saw the lead-up to his fight against Jon Jones knows - was glowing in his appraisal of the Australian judoka.

Evans is the overwhelming favourite in the fight, but he believes you can't become a champion without testing yourself against a fighter like Kelly.

"He's tough guy and he's on a win streak," he said.

"He has a big opportunity to beat a former champion just to show that it's not just luck and he is at the highest level.

"At the end of the day I want to be challenged ??? when you look at the top guys, it's impossible to get to the top place without fighting someone like Dan Kelly, someone who is resilient, someone who is mentally strong, who has an immeasurable amount of will.

"You can't be a top guy in the weight class without facing a guy like that, so for me to face Dan Kelly is me earning my spot with the top ranking guys."

Evans' road to 185 pounds has been tumultuous to say the least.

He was scheduled to fight Tim Kennedy twice, first at UFC 205 in New York then a month later at UFC 206 in Las Vegas.

Both times the governing commissions refused to grant him a medical licence to fight, citing irregularities in his pre-fight medical - specifically, issues with his MRI scans.

Evans said the relief when he was cleared to fight this weekend was unbelievable, before clarifying the issues with his scans - to an extent.

"I'm so thankful I got cleared, it's been a long journey, it was a tough time for me ??? it's my livelihood, and it's scary to have that being threatened.

"Whenever you do an MRI it has to be read by a radiologist, and whatever they report becomes what is, but what the radiologist was reporting wasn't actually what was, so I had to go and see a specialist to prove the radiologist read the reports wrong.

"It was very frustrating, It hurt but sometimes that's the way things go, but that's how life goes sometimes."

If Evans can get past Kelly, and he is the heavy favourite, GSP or Bisping may have a new threat to contend with in the middleweight division.