Carlos Alcaraz’s comeback victory against Jannik Sinner at the French Open final in June, an enthralling, edge-of-the-seat five-set thriller, perhaps unreasonably heightened expectations that after the close of men’s tennis’ golden era, this is the new rivalry upon which it will hinge.But both protagonists have lived up to the billing. Sinner and Alcaraz – World No. 1 and World No. 2, 1A and 1B in the sport’s pecking order – have not only built a strong inter-personal rivalry but also separated themselves from the chasing pack in a way that very muted expectations remain of any player being capable of stopping the duo, physical issues notwithstanding, from contesting the final at the US Open, which starts on Sunday.Since Sinner returned from his doping ban in the spring, both have played five tournaments each, and overlapped at four. They played each other in the final at each of the four, with Alcaraz winning three; the most recent of those victories came at the Cinicinnati Open – the most important tuneup ahead of the US Open – last week, where Sinner was forced to retire from the match due to illness.And if a massive gulf exists between them and the rest of the draw, only fine margins separate them.Unlike the summer, where the tennis is played on the natural surfaces of clay and grass, the hard courts are Sinner’s domain; and with expectations of them being particularly fast, it will make him even more of a favourite. The Italian has won each of the last three hard court Majors and while the retirement at Cincinnati may come as a slight physical and psychological blow, his confidence will remain sky-high given the fact that he was on a 25-match winning streak on this surface before that.Sinner’s strengths on hard courts are primarily thanks to his consistently dominant baseline play, far better than anyone on the tour, even Alcaraz. Not only do the consistent bounces on the hard courts allow the ball to come right into his hitting zone, allowing him to unleash his fluid, destructive groundstrokes from the back of the court; it also allows his flatter hitting – his forehand and backhand zip the court as opposed to landing heavy with a lot of topspin – to do maximum damage. This is a combination that has been too much for nearly anyone who has played him on the surface since the start of last year.While Sinner seems to only crack against Alcaraz – he has lost six of their last seven encounters, and trails their head-to-head 5-9 – it’s even less so on hard courts. And while Alcaraz seems to have a streak of fragility in him, letting his level fall too much in big moments at times, that quality seems to come out more on hard courts.Story continues below this adWhile the Spaniard is no slouch on the synthetic stuff, having won his first Major as a teenager at the US Open in 2022, he has not yet reached the same heights ever again; his best result at a hard court Major since then being a solitary semifinal. Timing has played a part in those results. In the last two years, he has been unfit or lacking sharpness at the start of the season, and run out of steam at the end. But there are technical reasons too.Controllables – like serve, return, rally tolerance and shot selection – seem to run away from him even when the spectacular weapons are on display. This seems to hurt him most on this surface, when he can’t just pull out breathless rallies from the baseline or employ variety in the form of slices and drops.But there is plenty the Alcaraz camp can be upbeat about. He has reached the final at each of his last seven tournaments and won six of them, making this year the most successful one of his career so far. His new service motion has been talked about plenty, and while its execution has been patchy, it is getting results. His service numbers at Wimbledon were best in class.The anticipation for a hattrick of finals will reach a fever pitch as the two march through the draw. And is there anybody who can stop them?Story continues below this adIn terms of a path, Alcaraz has the trickier one. He opens his campaign against the tall, big-servingReilly Opelka on Monday, which will be a test. An early test could be against Daniil Medvedev in the fourth round (who beat him in New York in 2023) and in his quarter is Ben Shelton, semifinalist for two years running in New York and perhaps the most in-form player other than the ‘Big Two’ on tour at the moment.He has also landed in Novak Djokovic’s half, on course to meet in the semifinal, instantly revoking memories of the Serb’s phenomenal, ruthless victory over him in the quarterfinal in Melbourne in January. Taylor Fritz, last year’s finalist and another home favourite, is in Djokovic’s quarter.Sinner will be far more confident about his path. He has a scheduled early test against Alexander Bublik (one of only two players to have beaten him this year) and a quarterfinal against British fifth seed Jack Draper, whom he beat in the semifinals in New York last year. Alexander Zverev, who has had a dour season after some near misses at Majors, or Alex de Minaur, could face him in the semis.Story continues below this adBut at the start of the tournament, are any of these challengers really at the Big Two’s level? Truthfully, not really. It is likely to be another Major where the margins are decided by the top two, and if it results in another final, nobody is likely to complain.Men’s singles: Reilly Opelka vs (2) Carlos Alcaraz; (13) Daniil Medvedev vs Benjamin Bonzi; (7) Novak Djokovic vs Learner Tien; Botic van de Zandschulp vs (11) Holger RuneWomen’s singles: Barbora Krejcikova vs (22) Victoria Mboko (WC) Venus Williams vs (11) Karolina Muchova Ajla Tomljanovic vs (3) Coco Gauff Alycia Parks vs (5) Mirra Andreeva