Anthony Joshua retains title and seals win No 17

Anthony Joshua holds aloft his IBF world heavyweight belt after defeating Dominic Breazeale. Picture: AP

It was only the second time in the 26-year-old Joshua’s career that he has required more than three rounds to see off an opponent – his  American counterpart faring slightly better before caving over in the seventh round.

Joshua, who improved his professional record to 17-0 since winning the Olympic title in 2012 in London, delivered a devastating left-right combination early in the seventh round – similar to those that stopped many of the  Briton’s 16 previous opponents – that sent Breazeale to the canvas so heavily it appeared the fight was over.

But, somehow Breazeale (17-1) got back to his feet, clinging to the last seconds of his undefeated professional record, before a further  barrage dropped him again.

It left the referee with little choice but to wave the action over, one minute and one second into the seventh round.

Joshua was patient throughout the opening round, frequently landing left jabs and the occasional hurtful right, even showing a previously-unseen head movement to evade a Breazeale counter.

In the second Joshua displayed greater aggression. He punched through Breazeale’s high guard, and repeatedly sought – and often successfully found – his opponent’s resistant head with uppercuts, left hooks and straight rights. Significant swelling was already appearing around Breazeale’s right eye.

What followed was a demonstration of Joshua’s relish of combat. Breazeale’s impressive punch resistance ensured he remained on his feet, and when he fought back and landed, Joshua responded with greater malice.

His inexperience showed at one point with punches that missed wildly, while Breazeale continued to absorb heavy punishment in the rounds that followed, particularly a perfectly-timed left hook midway through the fifth.

The most impressive performance of Joshua’s career culminated with that combination in the seventh, and he clinically finished.

“It was a matter of timing and a process,” Joshua told Sky Sports. “I only had two weeks off after my last fight (against Charles Martin in April) and now I want to have a nice bit of time off.”

Joshua is adjusting his plans after Tyson Fury was forced to postpone his rematch with Wladimir Klitschko after hurting his left ankle in training. Fury, who is also British, was stripped of the IBF heavyweight title last year but still holds the WBA and WBO belts.

“I was looking at Tyson Fury and I hope he gets better soon because I was hoping to get that in the winter,” Joshua said. “In the meantime, we’ll look at other opponents.”