Michael Bisping doesn't need to prove anything to anyone. Not after a legendary 17-year career in which he's tied for the most victories in UFC history. And not after recently losing the middleweight championship he dramatically came into late in his career.

Yet for some reason, the 38-year-old Bisping has decided upon a move -- returning Saturday as a late replacement to headline UFC Fight Night in Shanghai -- that can best be summed up as part stubborn and part crazy. 

Bisping (30-8) yielded his title on Nov. 4 to a returning Georges St-Pierre via third-round submission at UFC 217 in New York. Based upon the Englishman's own comments leading up to the fight, most expected him to retire if defeated. 

He didn't. And on just two weeks' notice, Bisping instead accepted an opportunity to replace Anderson Silva, his former foe, after the longtime champion failed a drug test. 

So when Bisping enters the cage on Saturday for UFC's first trip to mainland China (Bisping previously headlined their 2014 card in Macau), he will face respected contender Kelvin Gastelum just 21 days removed from his last fight.

Sounds crazy, right? Despite the thought of many that Bisping, already in shape from the GSP bout, simply decided to accept the headlining role on such extreme short notice as a way to to end his career on his own terms should he prove victorious. But that wasn't the case either, as Bisping announced he wants his finale to come at the UFC's return to London in March. 

This fight is all about competition for Bisping and the opportunity to remove the bitter taste of defeat so quickly.

"The fact that I lost [to St-Pierre], it bothers me," Bisping told MMAFighting.com last week. "I know if I had that fight 10 times, I'd win that fight 10 times. I know I would, but I lost to Georges and here we are with this gift from the Gods.

"I get a chance to exorcise my demons. I get a chance to get back in the win column -- all good things."

That doesn't mean Bisping's decision is a smart one. The oddsmakers agreed, installing him as a 3-1 underdog. 

Long a company man, Bisping won his lone UFC title in similar fashion in 2016 by accepting a rematch against Luke Rockhold on 17 days' notice and recording a shocking first-round knockout. He heard the news this time around about Silva being pulled while listening to the radio in a car and instantly reached out to UFC president Dana White. 

"I text Dana, I said, 'Listen, I know a guy that fought last week who has no injuries that can fight in Shanghai,'" Bisping said. "He texts back, 'interesting,' and I text back, 'very.' Twenty minutes later, I get a phone call. We agreed, we said we'd do it."

Originally given a 30-day medical suspension from the New York State Athletic Commission for the damages accrued at UFC 217, Bisping was forced to undergo testing, including an MRI, to get cleared for Gastelum. It's a process he called "a pain in the ass," but ultimately worth it.

UFC Shanghai fight card

FavoriteUnderdogWeightclass

Kelvin Gastelum -305 

Michael Bisping +255

Middleweight

Li Jingliang -175

Zak Ottow +150

Welterweight

Alex Caceres -150

Wang Guan +130

Featherweight

Muslim Salikhov -220

Alex Garcia +185

Welterweight

"I got a call from legal department saying, 'Mike, we need to know that you're there mentally and physically, how do you feel?'" Bisping said. "I said physically I'm fine, but mentally I'm wounded. The only thing that's going to make that right is if I'm able to fight again. I'm emotionally and mentally scarred, but physically I'm fine."

The move was a surprising one, especially considering his fight with GSP went into the third round with Bisping absorbing damage from strikes. 

Originally upset about Silva pulling out, Gastelum (13-3) was overjoyed to get a big-name replacement. The former "Ultimate Fighter" winner is just hoping to get the credit he deserves for facing Bisping and, if things go his way, winning it. 

"It doesn't matter to me, but it would be cool if I got a little bit of credit, too, for stepping up and accepting the fight," Gastelum told MMAjunkie.com this week. "This will be my third or fourth former champion that I've fought in the last 12 months. I don't think people have been giving me credit for the fights I've been taking in the last 12 months. This will be my third main event in a row. I'm just riding the wave."

Gastelum, 26, snapped an impressive three-fight streak in July when he was submitted by former champion Chris Weidman and isn't sure whether middleweight or a return to 170 will be in his future after Bisping.

Prediction

Despite the short turnaround, Bisping enters the bout with clear advantages in experience and size, with both a four-inch height and reach edge. Considering Gastelum is a blown-up welterweight who relies on his speed at 185 pounds, that could play a key part in how the fight plays out. 

Neither is much of a threat to control or finish the fight on the ground as Gastelum's wrestling will likely be canceled out by Bisping's historically stingy takedown defense. This fight will be won and lost in the standup. Should Gastelum look as explosive as he did in finishing Vitor Belfort in March (a victory that was changed to a no contest when Gastelum tested positive for marijuana), this could be a dangerous outing for Bisping. But it's not that easy to predict. 

Bisping remains an excellent kickboxer who knows how to control space. He has also maintained a very high pace and ability level despite closing in on 40. The same stubbornness that forced Bisping to accept this challenge has also helped him gut out close fights in recent years. 

The former champion's durability should serve him well here, making it a strong chance the fight goes the distance. It will likely come down to whether the grind of a short turnaround and a trip halfway across the globe ends up affecting Bisping negatively. Considering consistency has been the calling card of his career and a great reason for his success as a striker, it makes it hard to bet against him. 

Pick: Bisping via majority decision