CHICAGO — At the end of UFC 213, Yoel Romero was on his back when the injured Robert Whittaker put the final punches on Romero in unanimously outpointing him for the interim UFC middleweight championship.

Nearly 11 months later at UFC 225, Whittaker will put his eight-fight winning streak on the line against Romero in a scheduled five-round middleweight rematch at United Center on Saturday night.

The fight was in jeopardy when Romero missed weight at 185 pounds. Romero was one pound over in the first weigh-in, then .2 over in the second and final weigh-in. The fight was originally for the middleweight championship.

"It's a long flight to Chicago. If I travel 22 hours, I'm fighting someone, mate," said Whittaker, from New Zealand.

Whittaker (20-4) and Romero (13-2) headline a stacked UFC card that features five current and former UFC champions. The co-main event will feature a fight for the interim welterweight belt between Rafael dos Anjos (28-9) and Colby Covington (13-1).

"So what happens is, sometimes these things line up whether it's injuries or guys just, timing-wise, they're ready to fight again, this whole thing lined up perfectly for probably the best card we've ever had as far as talent goes, stacked from top to bottom. The fans in Chicago have responded," said UFC president Dana White.

Despite the unanimous decision, Whittaker had to gut out a grueling 25-minute brawl with all three judges scoring it 48-47. Whittaker had to play off an injured left knee that he initially injured in camp for UFC 213, then Romero compounded the damage in the first round.

"He made it much worst," said Whittaker, who visibly struggled through the majority of the fight. But on Saturday, Whittaker expects to be fighting at an optimum level.

"I'm really looking forward to this fight. I haven't felt this good ever, so I think Saturday you're going to see the best Robert Whittaker."

Although Whittaker, 27, may be what he perceives to be in the best shape of his life, he is cognizant of Romero's electrifying finishes. Romero, 41, has finished 85 per cent of his fights with a TKO or a KO.

"He catches you on the wrong day he puts you out. He's like a truck, he dangerously explosive. He's number one for a good reason. You have to give him the respect he deserves," said the champ at 185 pounds

Romero thought he let a few opportunities slip away where he may have been able to finish off Whittaker.

"In one moment in the fight I was able to finish him, but I did not do it. Now I want to finish him," said Romero.

Romero knocked out Luke Rockhold in the third round at UFC 221 to set up the anticipated rematch.