US Open: who can challenge Nadal, Federer and Djokovic?
Ahead of the final major of the year, we look at the non-big three contenders to reach the final at Flushing Meadows and perhaps break the big guns' grip.
For the vast majority of the 21st century, grand slam finals have largely been the domain of Novak Djokovic, Rafael Nadal and Roger Federer.
Their dominance, shared somewhat with Andy Murray, has defined the modern era of the men's game. However, it has been most regularly interrupted at the US Open, which starts on Monday.
Marin Cilic and Stan Wawrinka have each prevailed in the past five years at Flushing Meadows, with Kei Nishikori, Kevin Anderson and Juan Martín del Potro all reaching the final in that time.
The most likely outcome remains that the men's final will be contested by at least one of the big three but, ahead of the final major of 2019, we examine some of the contenders to gatecrash the showpiece.
The world number five is enjoying a breakthrough year and heads to Flushing Meadows as one of the form players on the ATP Tour. He reached successive finals at the Citi Open and Rogers Cup, easing past the likes of Dominic Thiem and Karen Khachanov en route to the showpiece of the latter.
His heavy 6-3 6-0 defeat to Nadal in that final may have provided cause for reticence. However, Medvedev continued his outstanding US hard-court swing by coming from a set down to defeat Djokovic in the semi-finals of the Western and Southern Open, before going on to beat David Goffin in the final.
His fightback against the best player in the world should raise confidence he can upset the established order. It will be tougher over five sets but on current form Medvedev appears the most credible threat to the big three.
Khachanov's year has not been quite as impressive as his Russian compatriot Medvedev. However, he too resides in the top 10 and has a victory over Djokovic to his name, having beaten the Serbian in the Paris Masters final last year.
He was impressive in seeing off Stan Wawrinka, rising star Felix Auger-Aliassime and Alexander Zverev at the Rogers Cup and showed signs he could form a grand slam challenge at his run to the quarter-finals of the French Open this year.
Marat Safin, the last Russian man to win a grand slam, was Khachanov's idol growing up. He has the game to potentially emulate his hero, but a 1-8 record against the big three will leave plenty sceptical of his prospects.
Though not in the same vein of form as Medvedev, Thiem deserves his place on the list having been the most consistent challenger to Djokovic, Nadal and Federer in recent times.
He has reached the last two French Open finals, losing to Nadal on each occasion. However, he defeated Djokovic in five sets at Roland Garros this year and played at a level in the final that would have seen him victorious were he facing anyone other than the 'King of Clay'.
The hard court provides more of a level playing field and Nadal needed a tie-break to beat him in five sets in the quarter-final at Flushing Meadows in 2018. Thiem also holds a 4-2 record against Federer, whom he beat at Indian Wells this year.
Eventually, Thiem's persistence in pushing this legendary trio to the limit will pay off and there is plenty of evidence to suggest the US Open could be the stage on which he reaps his rewards.
Roberto Bautista Agut
While the other four names on this list have their best years ahead of them, Bautista Agut is arguably enjoying an elongated peak.
He was a quarter-finalist at the Australian Open, where he showed his endurance with three five-set victories and pushed Djokovic to four sets in the Wimbledon semi-finals.
The 31-year-old has since found some consistency on the hard court, reaching the last eight in Montreal and Cincinnati, and came from a set down to beat Djokovic in Miami back in March.
That win, however, marked his only success against a big-three opponent. Bautista Agut has proven he can reach the latter stages of majors but, if the draw does not somehow open up for him, would need to overcome the history books to earn a first slam final berth.
Pouille's thrilling 2016 fourth-round triumph over Nadal at Flushing Meadows had the look of a breakthrough moment for the Frenchman, but since then he has not been able to record a single victory over the Spaniard, Djokovic or Federer.
The 25-year-old does, however, seem to enjoy himself on the hard court, securing the best slam result of his career on the surface as he progressed to the last four at the Australian Open before running into a rampant Djokovic.
He beat Khachanov before being thumped by Djokovic in Cincinnati and, though he has endured an inconsistent year, the high-points Pouille has experienced should leave him with nobody to fear outside of the three favourites.
Pouille is unquestionably an outsider, but if he can harness the form that saw him stun Nadal then he can at least afford to have hope of pulling off another shock and giving France a grand slam finalist to celebrate.