Novak Djokovic stands on the brink of history at French Open
Novak Djokovic can become only the second man in history to have twice held all four Grand Slam titles at the same time with victory at the French Open.
But a returning Roger Federer and rejuvenated Rafael Nadal will stand in his way.
World No 1 Djokovic completed his first private stranglehold of all four Slams with victory at Roland Garros in 2016.
Having clinched the 2018 Wimbledon and US Open titles and then a seventh Australian Open crown in January this year, the Serb is tantalisingly close to another "Djoko slam".
Federer and Nadal, with 20 and 17 career Grand Slam titles respectively, are ahead of 15-time Major winner Djokovic in total hauls. But they have never managed to hold all four of the sport's greatest prizes at the same time.
It is such a rare feat that only Don Budge (1938) and Rod Laver (1962 and 1969) - all calendar Grand Slams - have pulled off the sweep. Djokovic, who turned 32 on Wednesday, is playing down his potential date with destiny. After losing to Nadal in the Italian Open final last weekend, the Serb was in no doubt that it was the Spaniard who would likely be celebrating a 12th Roland Garros title in a little over two weeks' time.
"Nadal, No 1 favourite, without a doubt - then everyone else," he said.
However, he admits his Paris triumph of 2016 which gave him his first sweep, is fuelling his bid for history.
"There is an extra motivation and incentive to win Roland Garros because of the opportunity to hold all four Slams, something I did three years ago, and that gives me obviously reason to believe I can do it again."
Twelve months ago such confidence would have appeared reckless when he was shocked by Italian journeyman Marco Cecchinato in the quarterfinals, a defeat that sent him crashing out of the top 20 for the first time in over a decade.
This time he starts his campaign against Poland's Hubert Hurkacz, the world No43 with a potential quarterfinal against Germany's Alexander Zverev, who has still to get past the last eight at a slam.
Federer is returning to Roland Garros for the first time since 2015, having turned his back on claycourts to focus on Wimbledon.
This year marks the 10th anniversary of his only Paris triumph and should the 37-year-old defy the odds and clinch the 2019 title he would become the oldest Grand Slam champion yet.
But Federer admits his chances of seeing off Nadal and Djokovic are slim.
Nadal's three-set win over Djokovic in Rome was timely as it was his first title of 2019 and had followed three successive semifinal losses at Monte Carlo, Barcelona and Madrid.
The last two of those were against Dominic Thiem and Stefanos Tsitsipas, both of whom play with a one-handed backhand, just like Federer.
Thiem, the 2018 runner-up to Nadal at Roland Garros, has defeated the Spaniard four times on clay.
"There is a new wave coming through with the one-handed backhand that can counter some of Rafa's spins and lefty play," said Federer.