ALEX de Minaur became the third quarter finalist through to the last eight for the first time, with a straight sets win over unseeded Canadian, Vasek Pospisil. The world number 28 had a breakout year last year winning three titles, but was yet to win in the second week of a Grand Slam. That all changed overnight when he knocked off Pospisil, 7-6 6-3 6-2 to shake off an early challenge and extend his head-to-head with the former top 25 player to 3-0.

The match lasted two hours and 17 minutes, and remarkably the Australian was lucky not to find himself a set down after his opponent had four set points in the tiebreak. De Minaur went on to win six consecutive points to take out the set, and then go on from there.

“The first set was crucial, with some things going his way and then my way,” de Minaur said. “I went 2-6 down, but didn’t think I played a bad tiebreak and tried to stay calm. I’m just so happy with the way I played to beat Vasek. “He is very tricky and aggressive. I tried to stay calm and kept running.”

Pospisil’s serve was up and running with nine aces and an efficiency of 60 per cent, as well as a handy 73 per cent first serve points won. However the Australian’s comparable 80 per cent off his first serve and a whopping 63 per cent off his second was the difference. He also broke four times to one, and claimed 44 per cent of Pospisil’s return points. The Australian only hit 16 winners to the Canadian’s 43, but also had 13 unforced errors to 48. Now he has one of the biggest challenges in second seed, Dominic Thiem.

After a forgettable return to the Tour at the Western & Southern Open, Thiem is through to a quarter final after dispatching the youngest remaining player in the draw, in Felix Auger-Aliassime. As the only fourth round player born this century, Auger-Aliassime was up against it taking on the world number three, but pushed him all the way in the first set before the Austrian ran away with a 7-6 6-1 6-1 victory in just over two hours.

While Auger-Aliassime served 12 aces and hit 24 winners, he only won a total of 64 points for the day, as Thiem’s counterpunching ability was able to restrict the Canadian. He hit one less winner, but 27 less unforced errors, only dropping 22 points on serve.

“I was really nervous before the match,” Thiem said post-match. “I knew that I was going to play against an amazing opponent. “The second and third sets were 100 per cent the best sets so far in this overseas trip. “I’m starting to find that mixture that I had in Australia, offence and defence, and putting a lot of returns in play. “I’ll try to bring that form with me to the next round.”

Thiem was well aware he is a more experienced campaigner compared to his rivals that remain, taking on another young gun in de Minaur in the quarter finals.

“I’m probably one of the oldest players in the field, which is a bit surreal to me,” Thiem said. “He’s (de Minaur) a bit like Felix, absolute superstar [and] up-and-coming. “It doesn’t matter if the Big Three are here or not. “Everybody wants their hands on the trophy.”

The other huge threat to Thiem’s crowd is third seed, Daniil Medvedev. The Russian rolled through his fourth round match against American Frances Tiafoe in straight sets, barely breaking a sweat. After Tiafoe pushed him in the first set, the 24-year-old world number five dropped just one game on his way to a 6-4 6-1 6-0 victory, hitting 25 winners to just seven, and had only 18 unforced errors to Tiafoe’s 32. The match was by far the shortest of the day’s action, lasting just 98 minutes.

”I was lucky enough to get the early break, relax a little bit and then I started playing amazing tennis after that,” Medvedev said post-match. “I’m playing better with every match and I hope this can continue. I’m pleased with the fact that I’ve won all of these sets and didn’t have to stay long on the court. That’s always good when you’re playing a Grand Slam.”

The Russian is the only player through to the last eight without dropping a set and is deserving of favouritism given Thiem’s recent form prior to the event. To potentially face Thiem in a semi-final, Medvedev must first defeat 10th seed, Andrey Rublev in an all-Russian quarter final.

”He’s (Rublev) playing amazing this year and it’s really cool that we managed to be in the quarter-finals together,” Medvedev said of his close friend. “Of course, it would be better if we were playing a final. “On the court, there are no friends and he knows that also. “We’re going to have a good match.”

Rublev secured his spot with a four-set win over sixth seed, Matteo Berrettini. The Italian got the upper hand early to win the opening set 6-4, before Rublev hit back to claim the victory 4-6 6-3 6-3 6-3 in two hours and 42 minutes. Both players hit 34 winners, with Rublev hitting 16 less unforced errors (28-44) and four more aces (9-5), while breaking four times to one, all coming in the last three sets.

Tomorrow’s two quarter finals features 27th seed Croatian Borna Coric up against fifth seed German Alexander Zverev, followed by 12th seed Denis Shapovalov taking on 20th seed Pablo Carreno Busta. One of those four players will reach the US Open final, their first ever Grand Slam final.