It wasn't the most jaw-dropping announcement given the 185-pound title fight had been talked about as a clear option for months, with discussion ramping up since St-Pierre made his comeback official 12 days ago on February 17.
UFC president Dana White on Wednesday revealed via SportsCenter that St-Pierre's first fight back in the UFC would be a challenge for the belt.
Last month, White mentioned St-Pierre had broached the possibility of moving down to 155 pounds.
And two, both men have taken a majority of their most recent fights to a decision, which St-Pierre has been a master at out-pointing his opponents, with eight of his nine welterweight title defenses going to the judges. He is now riding a career-best five-fight UFC win streak that includes a harrowing victory over Octagon legend Anderson Silva.
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Bisping initially won his title with a dramatic first-round stoppage of Luke Rockhold in California. St-Pierre said he believed he was no longer under contract with UFC, claiming the promotion breached their deal by failing to meet a deadline to formally offer a fight. They think he's beatable and obviously, Georges St-Pierre is no different.
Ex-welterweight champ St-Pierre has returned to the UFC after a three-year lay-off. Home cage advantage, Canada for St-Pierre or England for Bisping, could saw things significantly. But that just got that carrot dangled in front of my face of a several-million-dollar payday. I want it for my children's sake, for my family, for when I'm retired so we can still live a good life. I want it for my family's sake.
St-Pierre admitted last year that he was anxious he would regret, years down the line, not coming back, especially because he felt "right now that I'm at my best ..."
One of the biggest stars in UFC history is one step closer to making his Octagon return.