Tyson Fury battled to a rugged points win over Otto Wallin as he fought for over nine rounds with heavy cuts to maintain his unbeaten record in a dramatic bout in Las Vegas.
The 31-year-old Briton, a 1-25 favourite with bookmakers, was expected to walk through Sweden's Wallin but a deep wound above his right eye was repeatedly checked by the ringside doctor, prompting moments of stunned silence at the T-Mobile Arena.
It was a punch in the third round that drew blood above the eye and Fury displayed greater urgency when officials began to show concern, switching from patient boxing to planting his feet in a bid to land heavy, destructive shots.
A barrage in the ninth forced Wallin to sway, before a hard right hand piled him into the ropes in the 11th as Fury came through the type of examination few expected with a unanimous 116-112 117-111 118-110 points win.
Fury was taken to hospital after the fight, with promoter Frank Warren confirming he was set to have micro-surgery on the cuts - one above the eye and one on the eye-lid.
"It was a great fight," said Fury afterwards. "I got caught on the eye and that changed the fight. For the majority, I could not see out of the eye, then there was a clash of heads and I got cut again.
"It was a good 12 rounds, he was tough. It's all heart and determination - if I can keep going I will do. He was 20-0 and didn't know how to lose, but I was the better man."
Wallin said: "I did everything I could, I tried my best and Tyson is a great champion. Nobody can question my heart or question that I'm a good fighter."
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Cuts create a man possessed
A heavy shot from Wallin in the 12th offered one more threat at the end of a tussle which thrilled those in the arena. With Fury bloodied and grinding out shots, cries of "Tyson, Tyson, Tyson" poured down to ringside, dragging more from him.
Wallin, who lost for the first time in 21 outings, was seen as an easy night's work on Fury's route to a rematch with WBC heavyweight champion Deontay Wilder, but the Swede's come-forward tactics delivered a true scrap.
Had the bout been stopped because of the cuts, Wallin would have won by technical knockout, and with ringside medics checking the gash during the sixth and before the seventh round, Fury was nearing a crisis scenario.
Just as he did when he climbed from the canvas to force Wilder backwards in the final round of their December thriller, the Briton fought fire with fire. His punches became menacing, his face filled with anger rather than poise and two huge right hands sent Wallin backwards in the seventh.
A hard hook on the ropes in the ninth began another onslaught, with Fury glaring into the eyes of his resilient rival on the bell like a man possessed.
Wallin's trainer, Joey Gamache, clutched his towel in the 10th and the concern on his face made it appear he may draw an end to proceedings. His charge deserves immense credit after what was his first bout since the death of his father.
And Fury, too, deserves plaudits as he showed an orthodox stance, southpaw stance, hit and move tactics, and, ultimately, immense grit in his fifth bout since a 30-month spell out of the sport. Not for the first time in recent memory, he served up a compelling watch in testing circumstances.
A grand Mexican entrance
The downside for Fury is he will inevitably attract criticism over the fact only 8,249 of the 20,000 seats at the arena were filled.
Concerts featuring the likes of Calvin Harris and Drake on the strip may have played a role, but Fury will probably care little as this was in many ways a bucket-list event for him on Mexican Independence Day weekend.
Mexico's Saul 'Canelo' Alvarez has taken this Las Vegas fight night in the past two years, while the likes of Oscar de la Hoya and Floyd Mayweather have filled the coveted fixture in the past.
And Fury entered the ring in a style befitting an occasion, sporting a poncho featuring the Mexican flag and a sombrero, and then boarding a parade float for his journey to ringside.
Those here could have been forgiven for thinking such an entrance may have fallen flat with a routine win, and early on it felt like Fury was toying with his opponent - before he found his range with a three-shot combination in the second round.
It looked like he was slipping into gear, only for Wallin to turn what could have been a boxing exhibition into an up-close, blood-filled tussle.
Some may ask what Fury gets out of beating the likes of Wallin. The answer is money, further profile in the US and, crucially, the type of in-ring activity he simply did not have when, just six-months into his comeback, he faced Wilder last year.
When the cuts heal, this will have further developed his engine and ring craft - and ultimately done him no harm at all.
What now for Fury?
Before Fury left the ring, his white shorts now a light shade of red, he had already mentioned American Wilder as his next opponent.
Both have repeatedly spoken of a rematch, which, if you listen to the Briton, is slated for 22 February.
That date looks a tall order given Wilder should have a fixture with Luis Ortiz in November and, as is the way in boxing, the rumour mill says he may have plans that do not include Fury.
Fury has said he would explore legal options if the 33-year-old goes elsewhere and he has even spoken of fighting in December to keep sharpening his skills in readiness.
Promoter Bob Arum this week barked that "he's not fighting in December" because he wants to take any risk of a slip-up out of the equation. After Saturday's cuts, fighting again this year is now an impossibility.
Wilder may feel Fury's scare in Las Vegas shows he can get at his rival if they meet again. Team Fury will undoubtedly think their man is in far better shape now than he was in their Los Angeles thriller.
This hard-earned win was a case of job done. As those in attendance spilled out of the arena and back on to the famous Vegas strip in search of good times, fans around the world will now hope all roads lead to an adventure with Wilder.
'As weak as a kitten'
Tyson's father, John Fury, said he was "proud" of his son for "how he mauled his way through", but also claimed changes needed to be made to the fighter's preparation and team.
"It's the worst I've seen from Tyson," he told BT Sport Box Office. "He has to be honest and say things are not right. For a man to be in that condition after eight weeks camp, it looked like he had nothing after round two.
"His strength and power went tonight. He was as weak as a kitten from the first round. At 18st 1lb, I've warned him and warned him. He is a 19st fighter.
"If I had my way, the lot [Tyson's team] would be gone. If they keep that team that will be his career [gone]."
On the two cuts around the right eye, John Fury said: "An injury like that could finish a career."
Fury's trainer Ben Davison defended himself and said he was "happy" with his fighter at the end of a test few saw coming.