Fine margins. Sometimes, all it takes is a point won or lost, here or there, that decides the outcome of not just a tennis match, but an entire tournament. Such was the way for Rafael Nadal and Dominic Thiem.
Already down one defending champion on Tuesday, Thiem nearly brought about the loss of the other with a match that was almost certainly the greatest of his life. All it needed was the bow on top to wrap it up – instead, down 6-5 in the final set tiebreak, he let it out of the box with one poor overhead.
It was the sort of shot he’s made a thousand times – indeed, one of those times was just a few points earlier. A lob thrown up in desperate defence, deep enough to make you backpedal, but easy enough to get under and hit. Maybe it was fatigue, maybe it was nerves, but instead of ending the point resoundingly, Thiem sailed it out, and Nadal was marching on.
Maybe Nadal would’ve won the match otherwise, but the fact remains, that is how he did win it, and on the very real chance he goes on to win this tournament, it will be the shot that both defines his victory. From nearly out, to very much still in, while Thiem, can only replay it over and over in his mind, the question forever being, “what if?”.
In any case, we move on, with four more quarterfinal matches to come on Wednesday. Read on for a look at each of them.
All matches on Arthur Ashe Stadium (12:00pm start)
Naomi Osaka (JPN)  v Lesia Tsurenko (UKR)
Two players whose careers are on markedly different trajectories, young gun Naomi Osaka and 29-year-old journeywoman Lesia Tsurenko find themselves equals in experiencing a grand slam quarterfinal for the very first time. Having already beaten Tsurenko once as a 16-year-old at 25K level in 2014, and with a far more highly-regarded scalp in Aryna Sabalenka under her belt, Osaka comes into this one a commanding favourite, with the onus on the Ukrainian to find a way through her powerful game. A player of patience and angles, the difficulty for Tsurenko is that Osaka is unlikely to give her the time to work her way into points as each of her four previous opponents have, and that means she’ll need to be far more aggressive than she’s comfortable with. Maybe Osaka’s level drops and Tsurenko snatches a set, but realistically, this has a win for the Japanese written all over it.
Marin Cilic (CRO)  v Kei Nishikori (JPN) 
A rematch of the 2014 final, Kei Nishikori will be hoping for a vastly different result when he squares off again with Marin Cilic. A 6-3, 6-3, 6-3 affair Cilic won with relative ease, Nishikori never managed to find his way in that final, but with an overall head-to-head lead of 8-6, the Japanese certainly has reason to believe things can be different this time. Certainly he has to feel encouraged by what Alex De Minaur nearly did to Cilic in the third round, and should similarly look to use his mobility to frustrate the big Croat’s attempts to hit through this particularly slow Ashe court, albeit with his own offense to come from the backhand instead of forehand side. Of course, it’s not like De Minaur actually won that match, and if Cilic keeps the offensive footing he found against David Goffin on Monday, he could have another relatively easy night.
Night Session (7:00pm start)
Carla Suarez Navarro (ESP)  v Madison Keys (USA) 
Suffice to say, it’s been a good few weeks for Carla Suarez Navarro, who after essentially sleepwalking her way into the New Haven final, finds herself in her second US Open quarterfinal, squaring off against 2017 finalist Madison Keys. Holding a 3-0 head-to-head advantage, Keys comes into this one a definite favourite, yet considering Suarez Navarro’s significantly harder route here (Caroline Garcia, Maria Sharapova) and the added wrinkle that all of those losses have been in three sets, there’s definitely potential for an upset. Whether Suarez Navarro can pull it off will come largely down to how her offensive execution matches up with the American’s, and if she’s able to counter-punch for some winners early Keys could begin to fade. Still, with the crowd behind her you have to like Keys’ chances to move on — as long as her head allows it.
Novak Djokovic (SRB)  v John Millman (AUS)
Despite his early-round stumbles, there’s no denying Novak Djokovic is looking an awful lot like the man to beat this tournament, well… apart from his next opponent, the GOAT, John Millman – aka Johnny Millz, aka John Millionaire, aka “The Milkman”. In all seriousness, having already reached his Everest in knocking-off an ailing Roger Federer, it’s hard to see an outcome where Millman manages to repeat the feat against Djokovic, short of paying someone to sabotage the air conditioning and hoping the old, soft Nole shows up. If there’s any silver lining, it’s that he’ll most likely have the crowd on his side, and Djokovic will give him a ball he can at least try to tee-off on, but let’s be honest: the Serb eats guys like this for breakfast (or in this case, dinner), and he’ll be doing well just to lose sets with one break of service.