The Tour de France opens with a short, fast, team time-trial in Barcelona on Saturday, the first round of the battle to decide who will wear the coveted yellow jersey on the Champs-Élysées in Paris.
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Many of the tougher mountainous stages are packed into the final week, but there will be opportunities to make a difference before then.
Here, we look at five key stages that will determine who, if anyone, can dethrone reigning champion Tadej Pogacar.
STAGE 6: PAU TO GAVARNIE-GEDRE, 186KM
Saturday's team time-trial will give the more powerful squads a chance to flex their muscles, while the punchy climbers will come to the fore on the short, steep climbs that close out Sunday's second stage, which also finishes in Barcelona.
But it is the sixth stage, passing through the Pyrenees, which provides the first chance for significant time gaps between overall contenders.
While the final climb is long at 18.7km but not steep (3.7 per cent), before then the peloton must scale two behemoths: the Col d'Aspin and Col du Tourmalet.
The latter is 17.1km-long at 7.3 per cent and although its summit is 40km from the finish, Thierry Gouvenou, who designed the route, insists that "it packs a serious punch".
STAGE 10: AURILLAC TO LE LIORAN, 167KM
The day after the first rest day happens to be Bastille Day.
Home riders desperate to win on the national holiday will ensure an enthralling day of racing, while the hilly route, with seven categorised climbs, promises action among the overall contenders.
When the stage last finished at the small ski station in the Massif Central in 2024, Jonas Vingegaard pipped Pogacar, who had attacked on the final climb, in a razor-tight photo finish.
STAGE 15: CHAMPAGNOLE TO PLATEAU DE SOLAISON, 184KM
This stage will be run a few hours earlier than the World Cup final in the United States.
As an appetiser, though, they do not come much tastier.
The final climb to Plateau de Solaison is brutal at 11.3km and nine per cent.
It is one which many riders have already tackled this year in last month's Tour Auvergne-Rhone-Alpes.
Pogacar's teammate Isaac del Toro won that day on his way to overall victory in the week-long stage race.
He will have some tips to pass on to his team leader.
With the shorter, but steeper, Le Saleve - Col de la Croisette (4.6km at 11.2 per cent) just before the riders tackle the final ascent, expect overall hopefuls to leak out of the back of the leading group.
STAGE 16: EVIAN-LES-BAINS TO THONON-LES-BAINS, 26.1KM TIME-TRIAL
This 26.1km individual time-trial has three parts: a nine-kilometre-long climb, a rapid and technical descent, and then a flat 10km run to the finish.
Three years ago, Vingegaard put more than a minute-and-a-half into Pogacar on a similar-length time-trial en route to defending his Tour title. The gaps in this race against the clock could also be significant.
STAGE 20: LE BOURG-D'OISANS TO ALPE D'HUEZ, 171KM
"It's the hardest penultimate stage we've ever designed!" said Tour director Christian Prudhomme of this mountainous run.
On paper, it looks torturous with more than 5 450 metres of elevation gain, including four of the toughest climbs on the Tour.
"The idea is that anything could still happen regardless of the gap between the yellow jersey and his rivals," added Prudhomme.
"Because if you're a little bit off on a stage like this, it won't be seconds that you lose."
Before the final climb, which finishes at the top of Alpe d'Huez, there are the back-to-back Telegraphe and Galibier mountains, where, in 2022, Vingegaard's Visma team set about trying to crack Pogacar, who was in the yellow jersey.
Vingegaard and his teammate Primoz Roglic took it in turns to attack Pogacar, forcing him to repeatedly chase them down.
On the final Col du Granon climb, the Slovenian's legs went, and Vingegaard gained almost three minutes and a decisive advantage en route to his first Tour success.