Winning the Tour de France and Giro d'Italia in the same year is one of the toughest things to do in cycling.
In fact, it hasn't been achieved since 1998 and only six men in the history of the sport can claim to have done it as follows.
1949: Fausto Coppi (Italy)
1952: Fausto Coppi (Italy)
1964: Jacques Anquetil (France)
1970: Eddy Merckx (Belgium)
1972: Eddy Merckx (Belgium)
1982: Bernard Hinault (France)
1985: Bernard Hinault (France)
1992: Miguel Indurain (Spain)
1993: Miguel Indurain (Spain)
1998: Marco Pantani (Italy)
That list is unbelievably elite, with some of the best names to ever step onto a bike residing on it.
Tadej Pogacar will aim to add himself to the elite company this year though. After blitzing through the Giro d'Italia, he backs up at the Tour de France as favourite to wear yellow into Nice.
All things considered, he is a real chance of doing so. Jonas Vingegaard, considered his biggest rival, hasn't had a day of racing since April when he suffered a horrific crash at the Basque Country race, and was no sure thing of being on the start line for the Tour de France until as recently as last month.
Primoz Roglic is now 34 years of age and yet to break through at the Tour, while the jury is still out on most of the remainder of the field.
Following 1998, Lance Armstrong dominated the Tour de France - although he has now been stripped of all those titles - for six years, and no one else got close to the Tour after winning, or even finishing high up, at the Giro.
Russian Denis Menchov finally bucked the trend in 2008, finishing fifth at the Giro and third at the Tour, but his split preparation meant he wasn't close to either race realistically, losing to Spaniard Alberto Contador in Italy, and another Spanish rider in Carlos Sastre at the Tour.
Alejandro Valverde would finish sixth at the Giro and third at the Tour in 2016, but the struggles of riders attempting to win both races have been clear to see.
Pogacar comes in as favourite, but he will have to defy history to take the yellow jersey to Nice.