Paris- Chris Froome could face his toughest Tour de France challenge so far in 2018 after organisers on Tuesday unveiled a route and format that are potentially unfavourable to the reigning champion.
The race, which starts on the island of Noirmoutier off the Vendee coast on July 7, lacks a long, flat individual time trial where four-time winner Froome often pulverises opponents.
Six mountain stages and four hilly stages are packed into the latter part of the Tour before it ends on the Champs-Elysees in Paris on July 29.
"It's different every year and it's difficult every year," Froome said.
"I like the look of the Alpe d'Huez stage, for me that's the 'Queen' stage on this Tour," he added, referring to the potentially decisive, gruelling mountain climb.
Another tester will be stage nine, which follows a cobbled road to Roubaix, echoing the Paris-Roubaix one-day classic.
"It's a massive challenge with a lot of windy dangerous stages, I wasn't counting on racing Paris-Roubaix this year but I'll have to re-evaluate that now," Froome joked.
"It's going to be a very nervous race until we reach the Alps," he said
Such relentless hill and mountain terrain may well grind down Froome's protective entourage who have so successfully snuffed out attacks in recent Tours.
British sprinter Mark Cavendish said he was not looking to the hilly challenge.
"There's lots of sprint opportunities early on but the second bit, I'm not really sure I'll get that far," said the Quick Step rider with 30 Tour de France stage wins to his name.
The much lighter Briton Simon Yates, the 2017 winner of the white jersey for riders under-25, had other concerns.
"I'm a very light man, so I'm not looking forward to the wind in the Vendee," said Yates, who rides for Orica.
On top of that, teams will be allowed just eight riders in 2018 rather than the usual nine, leaving Froome less protected by his Sky teammates than he has been used to.
The 2018 route for the world's most prestigious cycling race is basically split into two sections.
The first is largely flat but features a series of potentially punishing challenges.
They include a 35-kilometre (22-mile) team time trial on day three on windswept plains, then a Brittany run to the pretty seaside town of Quimper on day five featuring 10 hills.
The route designers have also built in two ascents of the feared Mur de Bretagne while on stage eight and the day after comes the cobbled road to Roubaix.
When asked if the 2018 route would be tough for Sky captain Froome, Tour de France director Christian Prudhomme said all the riders taking part were champions.
"But the winner will need the stamina to roll through windy plains and do well in the team time-trial, he'll need to be able to resist the cobbles and have enough steam to get through all the mountains," Prudhomme told reporters.
"I know of a few such specimens from the Netherlands and from Britain," he joked, without referring to Froome or the 2017 Giro d'Italia winner Tom Dumoulin by name.
Route designer Thierry Gouvenou said the switch between the two sections "is perhaps the greatest challenge of this Tour".
After a rest day on which the riders fly from the north coast to Annecy, there follow three visually stunning Alpine mountain stages, four hilly stages and three Pyrenean mountain stages inside a breathless 12 days.
Many of France's great mountains will feature, such as the Alpe de Huez and the Col du Tourmalet.
But the two key mountain challenges are a brutal, uphill 31km individual time trial and a short 65km 17th stage featuring 38km of climbs to a summit finish at the Col de Portet.
Portet is the highest summit, at 2,215 metres, ever to feature on a Tour de France.
Gouvenou said team strategy would be crucial.
"There're only eight riders per team so it's a real strategic decision between the rollers and the climbers.
"And there are a few other surprises hidden in there along the way," he promised.