Stan Wawrinka vs Grigor Dimitrov is newest running joke among tennis fans.

The two one-handed backhand boys have played each other five times in the last 14 months with three of those meetings coming at Grand Slams and four being in the first round of a tournament.

Wawrinka has won all of them, even when Dimitrov was the third seed at Wimbledon while he was world No 224 and even when the Bulgarian was ranked way lower than him at the recent Montreal and Cincinnati Masters.

Essentially, their frequent early meetings at big tournaments are the symptom of their tennis condition – inconsistency.

Of course, pegging a three-time Grand Slam champion in the same category as Dimitrov may ironically seem inconsistent with their positions in the tennis pantheon. While Wawrinka peaked at three Majors across three years to blow the Big Four wide open momentarily, Dimitrov has merely teased his potential winning the Cincinnati Masters and then the ATP Finals in 2017.

However, both former world No 3 players are not really known for their stability on tour. And the external factors didn’t help matters either.

Wawrinka suffered a knee injury that pushed him out of the Top 250 while Dimitrov was bogged down by injury and mental fatigue that saw him drop down the ranks after being behind only Roger Federer and Rafael Nadal at the end of 2017.

But on Sunday, both reached the quarter-finals of the US Open... marking a crucial moment.

The Swiss 23rd seed beat defending champion Novak Djokovic in a rematch of the 2016 US Open final, after the top seed retired at 6-4, 7-5, 2-1. The Bulgarian world No 78 beat 38-ranked Alex de Minaur – who had earlier knocked out seventh seed Kei Nishikori – 7-5, 6-3, 6-4 to reach his first quarter-final since January.

Reaffirmation for Wawrinka

For the 34-year-old Swiss, who also reached the French Open quarters (beating Dimitrov!), it was a reaffirmation that he is still the player who can challenge the Big Three.

At Roland Garros – a year after a first-round loss pushed him to world No 263 – he beat Stefanos Tsitsipas in an epic five-setter but went down to Federer in the quarters. At Wimbledon, Rogers Cup and Cincinnati he lost in the second round to younger opponents. The 2016 US Open champion needed four sets in the first two round in New York.

But against Djokovic, for the first time since his return from multiple knee surgeries in January 2018, he looked like a three-time Grand Slam champion. He has notched several good wins in the last 20 months but this “walkover” over Djokovic should give him more confidence that most of them.

In the first set, he took his time to settle in, as Wawrinka often does. But once he fired up to saved three break points in the fourth game with sizzling serves, there was the ‘Stanimal’ mode on.

He blazed his groundstrokes – the same cracking shots that have beaten Djokovic in two Major finals before – with the full-blooded forehand winner to end a 21-ball rally while serving for the set being one of the shots of the tournament.

Djokovic seemed to resume normal proceedings when he broke early and took a 3-0 lead in the second but once the 23rd seed broke back at 4-2, there was no looking back. His potent one-handed backhand was firing all cylinders and with the power and the depth he has, he put too much pressure on Djokovic’s injured shoulder.

A good indication of his superb touch was his interaction with the crowd – the cupping of his ear, the conducting of their cheers and the basking in the atmosphere.

“He’s relishing the opportunity to show what he’s made of again on the big stage,” John McEnroe said, and there was no better way to put it. Wawrinka may be erratic but when he is on the big stage, he is capable of massive things and it won’t be wrong to think of him as a genuine contender again.

He is up against fifth-ranked Daniil Medvedev next. US Open’s “villain” had beaten him in their only meeting before – the first round of Wimbledon 2017 which was the last match the Swiss played that year. But against the exhausted Russian who is playing his 20th singles match in four weeks with a crowd completely backing him, he will have the chance to reach semis again.

Relief for Dimitrov

For 28-year-old Dimitrov, his fourth-round win was the equivalent of an adrenaline jolt to his tennis. The former world No 3 is now world No 78 and has looked a pale shadow of himself. He lost his way, his coach Dani Vallverdu to Wawrinka and seemingly any shred of fortitude he had. For someone with a game as eye-pleasing as his, Dimitrov’s performance graph this season was an eyesore.

He started his hard-court season with a first-round loss to world No. 405 Kevin King in Atlanta and didn’t go beyond the first two round at any tournament he played since. (Again, Wawrinka comes in here)

At Slams, he had lost in the fourth round to Frances Tiafoe at the Australian Open, beat Marin Cilic and ran into Wawrinka at Roland Garros and lost to rookie Corentin Moutet at Wimbledon after being two sets up.

But an injury to 12th seed Borna Coric suddenly opened up a path and he made the most of it by somehow reaching first US Open quarter-final. In the fourth-round match against a younger De Minaur, the 28-year-old was at his agile best and showed what sensational tennis he is capable of. Take a look at this point.

Soon as his big weapons clicked into gear, he was able together consecutive wins in a week: something he hasn’t been able to do this year.

After a disastrous season peppered with first-round losses and crumbling against unheralded players, he has turned a corner and give himself a chance to revive his career. The problem is that the one-time Baby Fed will play Roger Federer for a place in the semi-final, someone he has never beaten before.

The decks may be stacked against it, but if they do end up meeting in the semi-finals, we will know that the tennis Gods indeed have a wicked sense of humour. But for now, the resurgence of the two one-handed backhand club members is a good throwback for tennis. The players who were in the Top 3, but could never quite maintain it.