Throughout the early days of Jack Draper’s young career, questions around his physical preparedness for his chosen sport followed him wherever he went. As he continually struggled with injuries and endurance issues alike, Draper never failed to hear from those who believe he did not work hard enough, carry himself with sufficient professionalism or care enough about his craft.

Those days are over. Forever. For the third straight match in Melbourne, despite his stunted preparation and the rust that caked his game, Draper made his commitment and passion plain to see as he left everything out on the court and somehow found a way to drag himself across the finishing line of yet another frantic five-set match he seemed destined to lose, drawing on his endless reserves of grit and heart in the process.

Related: Djokovic overcomes sickness in brutal defeat of Machac at Australian Open

Although he stood two points from defeat against an inspired opponent lasering winners from all parts of the court, Draper survived to reach the fourth round of the Australian Open for the first time in his career, outlasting Aleksandar Vukic of Australia 6-4, 2-6, 5-7, 7-6 (5), 7-6 (8) in three hours, 58 minutes, finishing just before 1am Melbourne time.

“I feel good,” said Draper. “Another long match. Obviously it was a really high level, both of us played great. I thought that he produced some amazing tennis, especially in the big moments on the big points, and he competed incredibly well, as well. Another long one, but a great contest.”

Vukic, playing in the third round of grand slam for the first time, said: “I left it all out there. Jack’s an incredible competitor who I have a lot of respect for. Unfortunately, one of us had to win.”

Over his three brutal wins, each contest decided in five sets, Draper has spent 12 hours, 34 minutes on court. A year after vomiting into a rubbish bin after surviving his first career five-set match in his Australian Open first round match against Marcos Giron, Draper is now 5-1 in tennis’s most gruelling test.

“My body doesn’t feel too great, lucky I’ve got a good physio,” said Draper, smiling. “Mentally, I’ve really competed hard. I’ve loved the atmosphere playing in front of so many people and just, it’s given me a lot of energy to keep on pushing and I’m surprising myself.”

The victory sets up one of the most highly anticipated match-ups of the tournament. He will next face Carlos Alcaraz, the third seed and reigning French Open and Wimbledon champion. In the immediate aftermath of his victory, Draper was not quite ready to discuss the Spaniard: “I’m just thinking about my recovery and [to] get off the court, to be honest. I don’t want to think about him yet,” he said, laughing.

After his pre-season was disrupted by a hip injury that forced him off the court, Draper has had to rely on his determination and heart against opponents rising to the occasion of facing a prominent seed. He had already broken new ground by twice coming back from the brink of defeat against both Mariano Navone and the home favourite Thanasi Kokkinakis to win both matches, the two longest of his career, in five sets. In Wednesday’s second round conquest, Kokkinakis served for the match at 5-4 in the fourth set.

It was clear from the beginning that the spectacle had inspired Vukic’s best level as he opened up with a barrage of forehand aggression and pinpoint serving. Although Draper played excellently to retrieve Vukic’s early break and take the first set, Vukic refused to let up his relentless aggression as he breezed through the second set.

He then broke serve at 5-5 in set three. Down 6-5 and set point, Draper finally lost his composure. He demolished his racket, provoking jeers from a crowd that had otherwise been quite restrained. As he seethed in his chair between sets, Draper then gestured to the crowd to keep the abuse coming.

But it was his response after that moment of frustration that showed his resilience. He immediately regrouped and spent the fourth set pressuring Vukic, who simply refused to break down.

At 5-5 in the fourth set tie-break, two points from defeat, Draper finally broke through, eviscerating a point-ending down-the-line backhand to reach set point, where he landed an excellent first serve before sweeping up a smash to force a fifth set.

For a while, that seemed to be it. Draper used the momentum to establish a 3-1 fifth set lead and the four break points he generated for a double break were akin to match points. But Vukic fought back, saving the break points, retrieving the break and matching Draper throughout the set. By the time they reached the decisive 10-point tie-break, the pressure was weighing heavily on Draper’s shoulders

As he has done throughout this unforgettable run to the second week, Draper shrugged off his nerves and saved his most bold, courageous play for the most decisive points deep in the tie-break, and he held his nerve to close out another incredible victory.