Crowd favourite Nick Kyrgios came from two sets down to beat Andreas Seppi in a five-set marathon in the last 16 of the Australian Open.

The 19-year-old Australian was able to save the game by forcing a tiebreak in the fourth, which he took to earn a fifth set and eventually claim a 5-7 4-6 6-3 7-6(5) 8-6 victory in front of a doting home crowd in Melbourne.

Seppi had originally produced some smart work in the first set to frustrate the towering Aussie, with the Italian eventually getting the better of his opponent to claim the first set 7-5.

Kyrgios, who had previously shown his frustration by throwing his racquet to the court, picked up his concentration in the second set as he broke Seppi in the fourth game to put some doubt in the Italian's mind.

The 30-year-old failed to be moved, however, and he profited from some lacklustre decision-making to claim the second set 6-4, as the teenage Kyrgios fell to a break in the 10th game following a strong forehand from his opponent.

The faltering Aussie looked to gather himself in the third as he saved an early break point to take a two-game lead, before a vocal crowd helped to push the 19-year-old towards claiming the set 6-3.

As night fell over Melbourne, Seppi continued to push towards a four-set victory, but Kyrgios hung on in the game having drawn level at 4-4 off his own service.

Things turned in favour of Seppi not long after when Kyrgios could only find the net, leaving the Italian with the chance to seal the game with his opponent serving to stay in the contest at 5-4.

Both players then raced through a game each which left Seppi looking to break again to claim victory, only for Kyrgios to come up with two standout aces to force a fourth-set tiebreak.

The youngster continued to endear himself to the home fans as he dictated with power to claim the tiebreak and move the game into a decider.

Kyrgios claimed only his second break point in the fifth set to establish a strong foothold at 2-0, although Seppi battled back with things level at 4-4 after a dip in concentration from the teenager.

Seppi was unable to hold out a surge from the Australian, however, as Kyrgios went ahead at 5-4 and he eventually beat off the resilient Italian to claim an 8-6 advantage in the final set of a memorable three-and-a-half hour contest.