Dominic Thiem dumped out Rafael Nadal with a sensational four-set victory in the Australian Open quarter-finals. The Austrian fifth seed held his nerve – just – as he won three tiebreaks in a 7-6(3) 7-6(4) 4-6 7-6(6) triumph over the world number one. Thiem served for the match at 5-4 in the fourth set but imploded spectacularly, three forehand errors and a double-fault gifting back the break, before he spurned two match points in the tiebreak. But just as Nadal threatened the most unlikely of fightbacks, the 26-year-old rediscovered his composure to scrape over the line and reach his first semi-final in Melbourne. He will meet Alexander Zverev in the last four with a spot in Sunday's final at stake. Roger Federer faces Novak Djokovic in the other half of the draw. "It was such a mentally tough situation," Thiem said when asked about serving for the match in the fourth set. "I couldn't handle it but I turned it around again in the tiebreaker. It was demons in the head, everybody has it. I was just rushing way too much, changing the tactics and that was wrong. "That's tennis, you have to deal with these situations almost every single game, so I'm very happy I won the tiebreak otherwise we would be in a fifth [set] now!" Nadal and Thiem are familiar foes and yet practically strangers on hard courts, with 12 of their previous 13 meetings coming on clay. It was the Spaniard who settled fastest on Rod Laver Arena, earning the first break, only for his serve to waver when attempting to see out the set – just as it did in his previous outing against Nick Kyrgios. The set went to a tiebreak. Thiem took it. The second set followed a similar narrative, Nadal failing to hold onto an early break and Thiem pinching the tiebreak. But Nadal has not amassed 19 Grand Slam titles without adversity and he stayed resilient, breaking at 5-4 in the third set as cracks finally started to appear in the unflappable Thiem. Could the 2009 champion force a decider? It looked probable when Thiem choked and then blew two match points from 6-4 ahead in the breaker. But a fortuitous forehand, skimming the net and evading Nadal's racket, set up another winning opportunity and this time he took it, staying alive in the rally and watching with relief as his opponent biffed a forehand into the net.