Anthony Joshua retained his world heavyweight titles after he knocked out Kubrat Pulev in the ninth round on Saturday night. Heavyweight boxing can be one of the most unpredictable and unforgiving arenas in sport, as Joshua learned when he suffered a shock stoppage loss against Andy Ruiz Jr 18 months ago, but he matched expectations at Wembley Arena as he battered the 39-year-old Bulgarian into submission. The end, when it came, saw Joshua jolt back Pulev’s head with a series of vicious uppercuts which dropped the challenger to the canvas. Somehow, the old warhorse staggered to his feet but a thunderous straight right hand ended the fight in dramatic fashion with Pulev stretched out on the canvas. In contrast, the opening round was an exercise in extreme caution from both fighters, with Pulev being even more wary than Joshua, who at least threw a few jabs. Joshua opened up in the second and landed a flurry of punches before Pulev responded with a left hook. But the same pattern of feints and exaggerated respect was suddenly replaced in the third round by a straight right from Joshua which rocked Pulev. The champion hurt the Bulgarian badly and even though Pulev made a bizarre shout of defiance, while clinging on, he was in desperate trouble. He was dropped by a brutal Joshua uppercut and struggled to his feet. In the fifth a big right hand from Joshua rocked Pulev who, courageously, fought back and had his best round of the fight. But Joshua ducked and weaved under the incoming blows, cracking a smile at the bell, which Pulev returned with a flash of his white gumshield. The rugged challenger tried to bully Joshua with punches to the back of his head but Pulev had to draw on all his toughness and defiance in round seven. Joshua rocked him again with heavy combinations but Pulev would not buckle. He tagged the champion with a big right hand. Joshua was in control as they moved into the eighth round but he had to be wary of some wild roundhouse swinging from Pulev – whose resilience was not matched by technical excellence. The champion was much more impressive as he finished the fight with clinical authority. Apart from securing a showdown with Tyson Fury, Joshua’s decisive victory also made a small slice of boxing history. His defeat of the brave Pulev came in the first world heavyweight title fight to be held in a biosecure bubble. A thousand raucous fans were allowed into the arena, marking the first occasion that a crowd had been allowed to attend a boxing promotion in Britain since the start of the pandemic. Floyd Mayweather was also a surprise supporter of Joshua at Wembley Arena. Joshua’s fans lifted the atmosphere but their socially distanced noise was a reminder of how much boxing, and the world, has changed this year beneath the shadow of Covid. Joshua’s victory is expected to be followed soon by confirmation that he will face Fury in a potentially riveting and astonishingly lucrative world heavyweight unification title contest next year. Eddie Hearn, the promoter, has predicted that a fight between Joshua, who owns the IBF, WBA and WBO belts, and Fury, the WBC champion, could rake in more than £200m and around 2.2m pay-per-views. This would be just the first bout in a proposed two-fight deal. For a brief spell on Saturday night all the fevered Fury and Joshua talk was set aside as Pulev climbed through the ropes with the apparent intention of ripping up these presumptuous plans. But Joshua had spent the last six months training hard and preparing diligently for Pulev, who has a decent jab, and he was in no mood to squander his grip on the fight or his world championship belts. Pulev’s impudence at the weigh-in, when he promised to “destroy” Joshua, had steeled him further. But perhaps the Watford-born champion was driven most by his determination not to ruin the huge opportunity that he had won for himself – in the form of the money-spinning extravaganza against Fury which also presents him with a further chance to elevate his reputation in boxing to a new level.