Dominic Thiem produced an immense display of focus and fighting spirit to overcome a two-set deficit, and a raucous crowd, to defeat Nick Kyrgios and reach the fourth round of the Australian Open on Friday. In the bear-pit atmosphere of Kyrgios's favourite John Cain Arena, US Open champion Thiem dragged himself off the canvas to secure a thrilling 4-6, 4-6, 6-3, 6-4, 6-4 win over the Australian showman. "That first match against Nick here on his favourite court with an amazing crowd, there are easier things to do," said the Austrian third seed, who sealed the victory with a majestic backhand winner down the line. "Surely that's one of the toughest challenges in our sport. Tonight was epic and a good last match before the lock-down, it's really sad to say." A cluster of Covid-19 cases in Melbourne means there will be <a href="https://www.thenationalnews.com/sport/tennis/australian-open-to-continue-without-fans-after-new-covid-lockdown-in-melbourne-1.1164735">no more crowds at the Australian Open</a> for at least five days but the home crowd got their money's worth, if not the desired winner. Thiem was shell-shocked for the first two sets, barely able to lay a glove on Kyrgios, who channelled the crowd's energy to produce some electrifying tennis. Kyrgios stormed to a two-set lead with an impish underarm ace. Yet from there Thiem dug in grimly, and stole the momentum from the Australian by serving like a machine. A frustrated Kyrgios smashed his racket into the court before surrendering the third set with a bungled 'tweener'. Suddenly it was the Australian's back against the wall as a resurgent Thiem began wielding his racket like a wand. In a moment of madness, Kyrgios bungled another 'tweener' rather than volley into an open court, squandering the chance for a 5-4 lead in the fourth set. Thiem made him pay with three booming returns to break and at the change of ends an angst-filled Kyrgios fired a ball high into the terraces to lose an automatic point for a second code of conduct violation. Moments later the match was level, as Kyrgios fired wide to concede the set. Thiem bided his time before breaking Kyrgios at 3-3 in a nerve-shredding decider. "That's ridiculous," Kyrgios said, after watching another Thiem winner sail past him before the Austrian knuckled down to serve out the match. Thiem will next face Bulgarian 18th seed Grigor Dimitrov, whose third round outing was the polar opposite. Dimitrov led Spain's Pablo Carreno Busta 6-0, 1-0 before the 15th seed retired injured. Thiem has recent experience of fighting back from two-sets down in a tense Grand Slam match having done so in last year's US Open final to win his first major title. On that occasion it was Alexander Zverev who let slip the advantage, but the German remains very much in the hunt in Melbourne after cruising into the fourth round with a 6-3, 6-3, 6-1 thrashing of Frenchman Adrian Mannarino. The sixth seed will take on Serbia's Dusan Lajovic, who bounced back from dropping the first set to Spain's Pedro Martinez to win 6-7, 7-5, 6-1, 6-4. Also through to the last 16 on Friday was Felix Auger Aliassime after the 20th seed came through a battle of the young Canadian hotshots, defeating Denis Shapovalov 7-5, 7-5, 6-3. Auger Aliassime next faces Russian qualifier Aslan Karatsev, who produced the performance of the day to dominated Argentinian eighth seed Diego Schwartzmann 6-3, 6-3, 6-3.