The pattern repeated for each of the final three rounds.
The 26-year-old Sydney-based striker won by unanimous decision, with all three judges scoring the fight 48-47 in his favour. Not capitalizing on the injured foot of Robert Whittaker. "You owe me a fight, man". "It was tooth and nail there but this is unbelievable", Whittaker said immediately after having his hand raised.
"I have a lot of support from the Australian crowd back home, I know this and I'm blessed to be in this position".
Battling back to take the third, Whittaker was even more impressive in the fourth frame, landing high kicks and punch combinations while slipping out of range to avoid Romero's best shots.
Remarkably, UFC strawweight champion Joanna Jedrzejczyk offered to step in with just hours to spare, but the Nevada State Athletic Commission refused to sanction her addition to the card on safety grounds.
For Romero, this defeat has snapped an eight-fight win streak and will likely set him back in the rankings.
The pair exchanged a few words inside the octagon after the fight, with Bisping voicing his displeasure at the sight of the interim strap.
Following his last fight, a TKO win over Chris Weidman in November that earned ESPN's 2016 Knockout of the Year, Yoel Romero looked up to a Madison Square Garden booth where champion Michael Bisping was standing and said, "See you soon, boy".
"At the end of the day, I've got to be me".
Whittaker has never been one to jump into the fray, and he says that's not going to change just because he's on the verge of a title unification bout and the biggest fight of his life.
"He's the champ for a reason".
"And Jeff, he showed so much heart, too". "Here, take that", he added, throwing his own belt to the canvas, "fight me for it".
Romero (13-2), an Olympic silver medalist in freestyle wrestling, dominated the first two rounds with his grappling.
"I sustained an injury earlier in the camp and I thought it would be 100 per cent by now and the bastard kicked it", Whittaker quipped. Later in the round Romero was badly hurt by Whittaker again, going for sloppy takedowns. While many feared the fate of the Brit against Romero, on the evidence of Saturday, Whittaker could in fact provide the tougher test.
Whittaker told Joe Rogan afterwards that if Romero had landed another couple of kicks, the fight might have been over. In the co-main event, in heavyweight action, Alstair Overeem beat Fabricio Werdum by majority decision (28-28, 29-28, 29-28). He is also unbeaten (8-0) as a UFC middleweight and his victims also include Souza, whom he defeated by split decision in December 2015.
To wrap up International Fight Week in Las Vegas, UFC 213 will be rounding out the week in style.