Played across all three surfaces, tennis's Grand Slams see the best players face off times in an attempt to write their name into the sport's history books.
Beginning in 1968, the Open Era saw professionals begin to compete alongside amateurs in Grand Slams, and we've taken a look at the most successful Grand Slam champions of the Open Era.
The Debate: Who's the greatest male tennis player of all time?
The Greatest - Sporting Rivalries: Roger Federer v Rafael Nadal
Winning span: 2008-2023
Australian Open: 10
French Open: 3
Wimbledon: 7
US Open: 4
While people may argue over who the best player of all time is, there's no arguing when it comes to the most successful. Establishing himself during the peak years of Roger Federer and Rafael Nadal, Novak Djokovic went from nearly man to an all-conquering machine.
Djokovic won his first major title in 2008 at the Australian Open, but from 2007 to 2010, the Serb reached six semi-finals and two finals with just one Slam to show for it.
In 2011, he'd win three of the four, an achievement he'd repeat in 2015, 2021 and 2023.
His versatile game has seen him win 10 Australian Opens, four US Opens, seven Wimbledons and three French Opens.
Winning span: 2005-2022
Australian Open: 2
French Open: 14
Wimbledon: 2
US Open: 4
Of tennis's 'big three', if you take away their most dominant Grand Slam, Novak Djokovic is on 14, Roger Federer is on 12, while Rafael Nadal is on eight. But the Spaniard's total domination of clay is something unlikely to ever be seen again.
When you add John McEnroe and Boris Becker's total Grand Slam wins, they still fall short of Nadal at the French Open.
Despite having never played at the tournament before, Nadal was seeded fourth for the 2005 French Open and won it, just two days after his 19th birthday.
For an entire decade, Nadal ran roughshod over all on clay, winning nine titles in Paris, with only the shock defeat at the hands of Robin Soderling interrupting the run.
Winning span: 2003-2018
Australian Open: 6
French Open: 1
Wimbledon: 8
US Open: 5
It's incredible to think that, but for a lingering knee injury that led to Nadal's defeat in the 2009 French Open, the career Grand Slam would likely have eluded Roger Federer.
Over his career, Federer made five French Open finals and lost to Nadal in four of them. But while clay was never Federer's favoured surface, he was supremely dominant on grass and hard courts, winning 10 of the 12 available Slams on the surfaces between 2004 and 2007, and winning five in a row at Wimbledon and the US Open.
Though age and injury started to take their toll, Federer re-invented his game in the latter part of his career, and took three more Slams in 2017 and 2018.
Winning span: 1990-2002
Australian Open: 2
French Open: 0
Wimbledon: 7
US Open: 5
Until the arrival of Roger Federer, Pete Sampras was the greatest grass player in the history of tennis, winning seven titles in the eight years between 1993 and 2000.
Fittingly, in 2001, Sampras would reluctantly pass the torch over to Federer when the Swiss beat the defending champion in the fourth round. Sampras would only win one more match at SW19, but did finish his career with a fifth US Open title in 2002.
Winning span: 1974-1981
Australian Open: 0
French Open: 6
Wimbledon: 5
US Open: 0
One of tennis's greatest enigmas, Bjorn Borg won an impressive 11 Grand Slam titles in his career - enough to rank fifth overall, yet his story poses the question: 'what could have been?'
Borg played in one Australian Open as a 17-year-old, severely restricting his chances at more Grand Slam wins. Borg only played at Wimbledon nine times, yet won five titles. He played at the French Open eight times and won six times.
He also never won the US Open despite reaching four finals. And after all that, the Swede retired at the tender age of 25. As the old saying goes, the brightest stars burn out the fastest, and few shone brighter than Borg.