One week ago, Jiri Lehecka had not won a match in the main draw of a Grand Slam. Now, he is an Australian Open quarter-finalist.

The Czech’s brand of heavy baseline hitting and silky net play proved too much for sixth seed Felix Auger-Aliassime to handle Sunday on Margaret Court Arena, where Lehecka powered to an impressive 4-6, 6-3, 7-6(2), 7-6(3) fourth-round victory.

“Honestly, it feels amazing,” said Lehecka. “It’s tough for me to find some words because what we’ve been through last year and now coming back to Australia. [I lost] in the first round last year, so of course if somebody had told me before the tournament that I would play like this, then I wouldn’t believe them, but I’m super happy that I’m through and I’m excited.”

The World No. 71 Lehecka fell in the first round at all four majors last season but has upset a series of top opponents across the first week in Melbourne. The 21-year-old, who finished his 2022 season on a high by reaching the championship match at the Next Gen ATP Finals, also upset 21st seed Borna Coric in the first round and 11th seed Cameron Norrie in the third round.

“Of course, all the guys I have beaten over here, all of them are incredible players and I must have played my best tennis,” said Lehecka. “[I had] to show all the cards I have to beat them. Coric in the first round, [Christopher] Eubanks in the second round and Norrie, now Felix. It sounds crazy, but it’s true, and I’m very happy and so excited to continue the journey.”

Lehecka has pedigree when it comes to stringing together victories against higher-ranked opponents. On his ATP Tour debut as a qualifier in Rotterdam last February, he upset Denis Shapovalov, Botic van de Zandschulp and Lorenzo Musetti to reach the semi-finals, where he pushed Stefanos Tsitsipas to three sets.

That ATP 500 event in The Netherlands also saw Auger-Aliassime lift his maiden tour-level title, but the Canadian struggled to find his best level in Sunday’s encounter in Melbourne. That was largely down to a high-quality all-around display from Lehecka, who matched Auger-Aliassime’s power from the baseline and frequently made forays forward to pressure his opponent.

Despite dropping the opening set, Lehecka showed no sign of panicking in his pursuit of a maiden victory against a Top 10 opponent at the fifth attempt. He notched his only break of the match late in the second set to level proceedings before dominating a pair of tie-breaks to wrap a three-hour, 13-minute win in which he won 80 per cent (33/41) of points at the net.

“I felt good even from the baseline,” said Lehecka. “I helped myself with my serve a lot. I know that Felix has a huge serve. He knows how to finish points after a big first serve, so I was trying to focus on my first serve as well and then when we both went into rallies I felt that I was able to beat him from the baseline [too].”

The Czech may now have the chance to avenge his Rotterdam loss to Tsitsipas in his maiden Grand Slam quarter-final, where he will take on the winner of Sunday evening’s clash between the third-seeded Greek and 15th seed Jannik Sinner.

Jiri Lehecka made his main draw debut at all four Grand Slams in 2022, his breakthrough season. But the Czech was unable to make his mark at the majors, falling short in the first round on each occasion.

What would the 21-year-old have said if told before the start of the season he would reach the fourth round at the Australian Open?

“I wouldn’t believe you,” Lehecka told ATPTour.com with a smile. “But deep in my mind, I always knew that results like this are possible for me.”

The World No. 71 has played mature beyond his years at Melbourne Park, defeating two ATP Masters 1000 champions — Borna Coric and Cameron Norrie — en route to the Round of 16. And the Czech shows no signs of slowing down.

“I felt like my game was there, but that I just needed to focus on some small details that can get me through these tough matches,” Lehecka said. “That’s something that I think we worked hard on a lot and focussed on every day and every practice. Now for me, the most important thing is just to stay focussed on the right things.”

If his efforts thus far at the year’s first major are a good indicator, Lehecka will be a consistent threat at the world’s biggest tournaments for years to come. Not bad for someone who grew up playing tennis for fun.

“Back in the days when I was playing tennis back home, it was only about enjoyment and I never had big ambitions to become a pro,” Lehecka said. “For me it has always been like a hobby and to do some sports that I liked.”

The Czech has athletic genes. His father, Jiri, was a professional swimmer and his mother, Romana, was a professional track-and-field athlete. Lehecka believes he inherited empathy from his mother and his work ethic from his father, who preaches that the best way to earn anything is hard work.

When Lehecka was three, he watched as his grandmother taught his older sister, Veronika, the sport. He wanted to give it a shot. But tennis did not become more serious for Lehecka until he moved to Prostejov aged 15 and began representing the Czech Republic in various events.

“I started to feel more like I would love to do that professionally and I really liked how all these players looked when they are playing on the big stages,” Lehecka said. “That was probably the moment when I took a looked at myself and said, ‘Yeah, I really want to be a professional tennis player and I really want to live a life like that.’”

Moving to Prostejov to attend a sports school was scary at the same time. Lehecka went to his new home without his parents.

“It wasn’t easy for sure but luckily for me, I had great friends over there that I still keep in touch with,” Lehecka said. “They helped me go through those difficult times when it was my first time without my family or anybody I knew to focus more on the tennis and focus on what I should do there.”

It was in Prostejov where coach Michal Navratil met Lehecka for the first time.

“What I was excited [about] was he was a very nice guy, always said hello to everyone. He was a kind guy,” Lehecka said. “Then of course when I saw him on the court he was very powerful. The strength from the beginning was in him.”

Lehecka reached No. 10 in the world as a junior, but his biggest splash to date came last February in Rotterdam. As a qualifier, he advanced to the semi-finals with wins over Denis Shapovalov and Lorenzo Musetti along the way before pushing Stefanos Tsitsipas to three sets. He was not intimidated by the big stage of the ATP 500.

That comfort under the spotlight became even clearer at the Next Gen ATP Finals in November. The Czech advanced to the championship match in Milan.

“When I ended the journey in the final and I just took some time off and took some time to get back on the ground and some time looking back at the Next Gen, I think that every match over there, every practice session, and all the media stuff around, everything helped me in a certain way,” Lehecka said. “These are the experiences that helped me to be more prepared for what came over here.”

Navratil believes that “something changed” in Milan for his charge.

“He started to believe more in himself,” Navratil said. “He had a couple of chances also during the year and he learned from it and he grew up and he got to this point and now he enjoys it and he believes he can beat anyone and I am so happy for it.”

Former WTA World No. 1 Karolina Pliskova has been following Lehecka’s progress through the tournament and was impressed with his five-set win against Cameron Norrie in the third round.

“He has a really good coach, who used to be around with Jiri Vesely. So I think that’s also helped him to bring some experience, but I think the game is quite strong,” Pliskova said. “I actually watched yesterday quite a lot of the match with Norrie. I think he’s very aggressive, especially on these fast courts I think it can pay off and of course he’s still like a newcomer for some of the players, so they don’t know him that much and I think he can do well.”

While Lehecka hopes to continue further in the tournament — he plays Felix Auger-Aliassime in the fourth round — and climb the sport’s ladder in the years to come, he wants the fans who begin to watch him to know about more than just his tennis.

“I just want them to know that I’m an honest person,” Lehecka said. “I really like people who are working hard and they are not trying to find any excuses.”