Jack Draper admitted that he is surprising himself with his marathon run in the Australian Open having reached the fourth round after surviving another five-set battle to book a clash with Carlos Alcaraz in Melbourne.

Draper, 23, went the distance for the third consecutive round as he defeated the Australian Aleksandar Vukic in a deciding match tiebreak, winning 6-4 2-6 5-7 7-6 (5) 7-6 (10/8) at 0055 local time [GMT 1355].

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

The British No 1 has been working hard on improving the physical and mental parts of his game, although his pre-season was disrupted by a hip injury that forced Draper to cancel a training week with Alcaraz in December.

Despite his lack of build-up, Draper has now spent more than 12 hours on court in his wins over Mariano Navone, Thanasi Kokkinakis and now Vukic, with the 15th seed also managing to stay relaxed in the big moments.

It was only a few months ago that Draper opened up on his anxiety and nerves following his US Open semi-final defeat to World No 1 Jannik Sinner, and the 23-year-old has revealed how he has worked on breathing techniques to deal with the stress of competing over five sets at the grand slams.

“Obviously there's always been that question mark in my head over five-set matches, and am I able to do it? From a mental side of things, and physical as well, is my body going to hold up?” Draper said afterwards.

“I've been putting in a lot of work in general over time. By having that time off with my hip, I was able to focus on working on a few different things. I was working a lot with a breathing coach and just trying to understand that a bit better.

“I had a lot of problems with my sinuses when I was younger so I breathe a lot through my mouth. When you are anxious or when you have long points and you have to recover quickly, it's not efficient to breathe through your mouth. So I've been trying to reverse what I do and breathe through my nose a lot better.

“I think sometimes you don't realise how uptight your body is. Especially me, because I've always been someone who likes to try hard. I think sometimes you have to relax, especially in tennis, because you need to be free to let your muscles do what they need to do. If you're tense the whole time, you're not going to last too long.”

Draper was aware of the criticism he has faced at times for failing to hold up physically at the grand slams and struggling. “It's the truth,” he said. “I'm done after two sets most of the time. I mean, that's just the way it is, and that's something that I'm aware of, and I needed to be better at that.

“I still have a long way to go, but this is a huge drive forward, the fact that I'm mentally and physically, three five-set matches, it doesn't happen often. That's a testament to the work I've done and the place I'm in.”

Draper quickly turned his attention to recovering for his fourth-round match with Alcaraz. Draper said he had felt “sore” after his previous win over Kokkinakis, and another late finish will hardly help his efforts to be ready for a clash against the four-time grand slam champion and third seed, who has breezed through to the last-32.

Draper defeated Alcaraz in their last meeting at Queen’s, but the British No 1 said he would not be reading too much into the victory. “I think he just came off the French Open and had a bit of time off. I had just won Stuttgart, and the grass is a completely different ball game,” Draper said.

“I know what to expect from him. He's going to come out with a lot of energy, and obviously he's a special talent. I need to be aggressive. I need to take my chances. Against the top players you get less and less chances to win games and sets.

“I need to be brave in the way I play, but I'm expecting him to come out and know that I've played three five-setters and know that he's got a battle on his hands, and he's going to have to play good.”