Parker (right) began to look more dangerous as the fight developed
Joseph Parker recovered from being knocked down in the opening 10 seconds to beat Derek Chisora on a split decision and keep alive hopes of a shot at the world heavyweight title.
The Briton floored New Zealander Parker at Manchester Arena with an overhand right to the temple.
But the former world champion turned the tide and landed combinations as the bout wore on, while Chisora tired.
It proved enough to earn a split decision 115-113 111-116 115-113.
Chisora, 37, felt aggrieved by the scoring and said: "I'm beyond getting upset now. It's difficult. I train hard. I put pressure on, this is the treatment I get from boxing.
"I was bringing it. I was doing more power punches and inside work. I won't let them slow me down. I will go again. I will not let them win. They want to see me retiring but I am not yet."
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Chisora had said he might withdraw from the fight because he had to walk to the ring before his opponent, a threat in keeping with the unpredictability he has served up in over 14 years as a professional.
Some have questioned why he still headlines pay-per-view cards after 10 previous career defeats but the looping right hand that sent Parker to the canvas served as an instant reminder of his threat.
As always, he looked to bulldoze his opponent with constant pressure but Parker – eight years his junior at 29 – was able to build momentum as Chisora slowly faded.
To Parker's credit, facing such pressure is mentally taxing but he stood up to both the knockdown and an early onslaught before beginning to land good combinations of his own.
In the seventh a one-two followed by a three-shot flurry sent Chisora back to the ropes and pointed to his vulnerability.
In the 10th Parker followed another one-two with an eye-catching short left hook and he teed off on Chisora again in the 12th as he closed in on a 29th win from 31 outings. Only British heavyweights Anthony Joshua and Dillian Whyte have bettered him.
Asked if winning a world title for second time is a possibility, Parker said: "It's very achievable. I just have to get back to training. There's still a lot I can show.
"It was very close fight. I thought it could go either way. He brought the smoke."
The former champion can look to bigger names but the stars at the top of the division possess natural size advantages that will make his task all the more tricky.
Chisora, in contrast, must search for a next move. He has shown time and again he can come up with something to go after.
Del Boy's conundrum – analysis
BBC Sport boxing correspondent Mike Costello:"I made Parker the winner by three rounds but wouldn't mount a strong argument against the judge who favoured Chisora. It was compelling heavyweight boxing and – coming after Taylor-Jonas – just imagine a night like that with a crowd.
"Parker did well to recover so quickly from the early knockdown and for me his cleaner punching at long and mid-range was decisive. His durability and resilience were also factors and, given more time with his new trainer Andy Lee, there should be better to come.
"Chisora's reputation won't suffer in losing such a fight and the Parker camp have said there should be a rematch – not a difficult sell."
BBC Radio 5 Live boxing analyst Steve Bunce: "Should this be Derek's last fight? Can you get enough money for risking your reputation? If there is something out there where he can make the same money or close to what he made tonight, then yes.
"What I don't want to see is him reduced to third on the bill and be there as a test for somebody.
"If there's another heavyweight out there he can generate that type of money with, let him fight.
"I don't want to see Derek become an 'opponent' – he's better than that."
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