French national champion Romain Gregoire looks to the future stages of the Tour de France after a punishing opening week in the mountains. Photo: AFP

Cycling's Tour de France has become so hard that only "global superstars" are able to win even a single stage, French champion Romain Gregoire moaned on Monday's first rest day.

Gregoire, who is a punchy racer but not a pure climber, won the French title a week before the Tour began in what had been the 23-year-old's best season to date, including Top 4 finishes in major one-day classics such as Strade Bianche and the Amstel Gold race. But he wilted under the intense heat and breakneck pace of the Tour's opening week and already finds himself an hour and a quarter down on race leader Tadej Pogacar in 60th place.

He finished Thursday's Pyrenean mountain stage in tears, more than 40 minutes after Pogacar, having struggled just to keep up with the peloton's burly sprinters.

"I think I can recover a pretty reasonable physical condition which should allow me to be competitive in certain stages," said Gregoire. "But when you look at what happened in the first week, you realise that every year in the Tour de France, it's only the global superstars who are able to impose themselves.