Jack Draper credited a change in his breathing technique for the improved physical endurance that has carried him to a fourth-round clash with Carlos Alcaraz at the Australian Open.

The British number one has come through three five-set matches at Melbourne Park to reach the last 16, battling back from two sets to one down each time.

Draper has struggled to last the distance in long matches, particularly in the heat, during the early part of his career, cramping in a number of contests and vomiting on court in Melbourne last year and during the US Open semi-finals.

He believes anxiety has played a part, but also revealed he used the time he was sidelined by a hip injury in pre-season working to alter the way he breathes during matches.

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

“I’ve been putting in a lot of work in general over time. It seems like maybe, by having that time off with my hip, I was able to focus on working on a few different things.”

He continued: “I was working a lot with a breathing coach and just trying to understand that a bit better. So I think that’s really helping.

“I had a lot of problems with my sinuses when I was younger, so I breathe a lot through my mouth. Obviously 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, and I think sometimes it’s just you have to relax. Especially in tennis, because you need to be free to let your muscles do what they need to do. So, obviously, if you’re tense the whole time, you’re not going to last too long.”

While Draper’s endurance has been impressive, he has not yet played in particularly hot conditions, with his second and third-round matches against Australian duo Thanasi Kokkinakis and Aleksandar Vukic staged at night.

He did not get off court after the Vukic contest on Friday night until gone 1am and had hoped for another night match against Alcaraz, but instead he will have to play through the heat of the day with the match scheduled on Rod Laver Arena at 3.30pm.

In more bad news for Draper, it is forecast to be the hottest day of the tournament so far, with temperatures in the mid 30s, so it will be a serious test of his already tired body.

The 23-year-old, who had never previously been beyond the second round here, has played in three of the 13 longest matches of the tournament and spent more than 12 and a half hours on court – more than twice as long as Alcaraz, who has only dropped one set.

On how he would try to recover, Draper said: “The main thing is just to not think about the tennis at all and switch off from it and try and just relax, and hopefully the body will be OK. I’m expecting to be really sore.”

Draper had been due to spend a week training with Alcaraz in southern Spain in December but that was scuppered by his hip injury.

The pair have played three previous matches and Draper can take confidence from having won their most recent contest at Queen’s Club last summer – although he does not consider that particularly relevant.

“The grass obviously is a win but I think he just came off the French Open and had a bit of time off,” said Draper. “I had just won Stuttgart, and the grass is a completely different ball game.

“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 and all these sort of things.

“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. It will be a great contest, I’m sure.”