The 2023 Tour de France starts in Bilbao on Saturday with two big favorites -- defending champion Jonas Vingegaard and two-time winner Tadej Pogacar, runner-up last year. 

AFP Sport looks at five things to know before the 110th edition of the three-week race. 

25th Start Outside France 

The Tour will kick off outside France for the 25th time. It will the second start from the Spanish Basque Country after San Sebastian in 1992. 

After two stages entirely in Spain, the peloton heads for Bayonne in France. 

In 2022, the Grande Boucle started in Copenhagen, and in 2024, it gets underway in Florence, Italy. 

Cities pay dearly for the right to host the Grand Depart, which race organizer ASO insists expands the international influence of one of the biggest sporting events in the world. 

A Very Mountainous Route 

With nearly 56,000 meters of climbing, a record 30 passes, five French mountain ranges and a single time-trial, this Tour presents a tough profile that favors climbers. 

After the Pyrenees, the Tour makes an eagerly awaited return to the Puy de Dome in the Massif Central after 35 years. 

The race then will climb through the Jura, the Alps, with the main stage to Courchevel via the Col de la Loze (2,304 m), and finally the Vosges, on the eve of the finale in Paris on July 23. 

Pogacar-Vingegaard Summit Duel 

Dane Vingegaard, winner last year after a second place in 2021, and Slovenian Pogacar, the 2020 and 2021 champion, then runner-up in 2022, are the big favorites, though Pogacar's form remains unknown after breaking his wrist April 23 during the Liege-Bastogne-Liege. 

For Vingegaard, the question first concerns his ability to resist the pressure of defending his title. 

At least a dozen other riders, including French duo David Gaudu and Romain Bardet, Spaniard Enric Mas and the Australian Ben O'Connor, could fight for podium places. Remco Evenepoel, Primoz Roglic and Geraint Thomas are the main absentees. 

Safety In Spotlight 

The death of the Swiss rider Gino Maeder in mid-June, descending a mountain in the Tour de Suisse, plunged the peloton into disarray and reignited the debate over safety. 

Accustomed to exceeding 100 km/h downhill, many riders shared their apprehension, while recalling that danger is an integral part of their sport. 

To limit the risks, organizers have planned measures, including the installation of padded parapets on certain turns to prevent riders from falling into the void. 

COVID Concerns 

In most sports, COVID-19 is only a distant memory, but cycling is resigned to another Tour under virus protocols. 

Organizers want to avoid the problems of this year's Giro d'Italia, when Evenepoel withdrew after a positive test while leading. 

As in the last three Tours, staff, journalists and guests will have to wear masks when in contact with riders who are advised to avoid selfies and autographs.