Chris Froome (Team Sky)
Nationality: British
Age: 32
Major grand tour results - Tour de France: 1st (2013, 2015, 2016), 2nd (2012); Vuelta: 2nd (2011, 2014, 2016)
Despite not winning a race this season, something he has never done before winning the Tour, Froome remains the overwhelming favourite.
Once again the Briton brings with him the world's strongest team who control the race, sustaining a fast pace in the climbs to prevent attacks from rivals, with Froome usually finishing the job at the end of each stage.
Last year, we saw Froome attack on all terrains, dropping his rivals in descents or on the flat.
He looked uncharacteristically underdone during the pre-Tour Criterium du Dauphine. But his experience should make the difference even if the treacherous route this year, with very little time-trial mileage, will not favour Team Sky. 
Richie Porte (BMC Racing)
Richie Porte aims to become the second Australian to win the Tour de France overall classification. (AAP) Source: AAP
Nationality: Australian
Age: 32
Notable grand tour results - Tour de France: 5th (2016); Giro d'Italia: 7th (2010)
Porte has certainly impressed this season winning the Tour Down Under and the Tour de Romandie. And his oh-so-close second place at the Criterium du Dauphine showed off his top form on the climbs.
Pundits talking down Porte point to his poor track record in grand tours where he can suffer an off day that kills his chances, not helpful considering many of the hard stages at this year's race.
But these bad days have often come while in the service of others, like ex team mate Froome. On his own, the Tasmanian's ability to fight back and climb with the world's best to a strong fifth place finish at last year's Tour after suffering time losses from a stage 2 puncture and that crash with a moto on Mont Ventoux was a case of what might have been.
And at this year's Criterium du Dauphine without BMC's strongest team, his "bad day" on the final stage saw him finish just 10 seconds from victory.
Downplay his ability to win this year's race at your peril.
Source: Getty
Nairo Quintana (Movistar)
Nationality: Colombian
Age: 27
Notable grand tour results - Tour de France: 2nd (2013, 2015), 3rd (2016); Giro d'Italia: 1st (2014), 2nd (2017); Vuelta: 1st (2016), 4th (2015)
One of the best climbers in the world and one of very few able to drop Froome in the mountains, Quintana has the grand tour runs on the board.
When Movistar and Quintana talked up his Giro d'Italia-Tour de France double chances, they pointed to the 36.5 kilometres of time trials at the latter, as if the 70 kilometres of time trial kilometres and Tom Dumoulin at the Giro d'Italia were insignificant.
But they weren't; Quintana losing one minute and 24 seconds to the Dutchman in the final 30 kilometre time-trial in Milan alone. He's bound to lose similar time at the Tour's races against the clock, and with a hard Giro already in the legs, Quintana might struggle to keep his form during the three weeks of the Tour.
Plus, he has shown in previous editions he is quickly happy to settle for second or third.
Or did the Colombian get that podium place out of the way already at the Giro, with one eye already on the Tour?
Last year's Vuelta victory shows Quintana improves at his second grand tour of the year and that's the fabulous unknown he brings with him as we ponder the podium top-step in Paris.
Romain Bardet (AG2R-La Mondiale)
Romain Bardet - pictured here at the 2017 Flèche Wallonne. Source: Getty
Nationality: French
Age: 26
Notable grand tour results - Tour de France: 2nd (2016), 6th (2014)
Kicked out of Paris-Nice for taking a team car tow, last year's Tour runner-up was forced to change his schedule, finishing 10th at the Volta Cicista a Catalunya and 15th at the Tour of the Basque Country. His top result before June was his sixth place at the one-day Ardennes classic Liege-Bastogne-Liege.
His 2017 Criterium du Dauphine displayed a mixed bag of form, looking strong on some climbs but out the back of the favourites on others. But he forged out a strong sixth place overall and he is unlikely to be as inconsistent over a three-week Tour, particularly one with many stages suiting his dapper style.
Fabio Aru (Astana)
Fabio Aru at the Vuelta a Espana (AFP) Source: AFP
Nationality: Italian
Age: 26
Notable grand tour results - Giro d'Italia: 2nd (2015), 3rd (2014); Vuelta: 1st (2015)
Aru was all set for a 2017 Giro d'Italia start in his home town of Sardinia until he was felled by a knee injury.
Turning his attention to the Tour de France, the Italian displayed strong form at the Criterium du Dauphine.
While he took a back seat as team mate and domestique Jakob Fuglsang rode a tactically brilliant final two stages to take overall victory there, expect the newly crowned Italian national champion to lash out as he looks to improve on his 13th place overall of 2016.
Alberto Contador (Trek-Segafredo)
Contador is muy tranquilo about his chances (Getty). Source: Getty
Nationality: Spanish
Age: 34
Notable grand tour results - Tour de France: 1st (2007, 2009); Giro d'Italia: 1st (2008, 2015), Vuelta: 1st (2008, 2012, 2014)
Contador's last Tour title dates back to 2009 and while he certainly does not have the same condition, the Spanish daredevil still has the sparkle. He is feared by all his rivals for his ability to launch long-range attacks.
The Spaniard has made the Tour his only goal of the season.
Alejandro Valverde (Movistar)
The ageless Alejandro Valverde will use his experience in support of Nairio Quintana. Source: Getty
Nationality (Spanish)
Age: 37
Notable grand tour results - Tour de France: 3rd (2015), Giro d'Italia: 3rd (2016), Vuelta: 1st (2009), 2nd (2006, 2012), 3rd (2003, 2013, 2014)
After an ominous start to the season with titles in the Fleche Wallonne and Liege-Bastogne-Liege classics, victories in the Tour of Catalunya, Tour of the Basque Country and Tour of Andalucia, Valverde took some time off and came back for the Dauphine.
He launched long-range attacks but failed to unsettle the best. A potential podium finisher in Paris even if Quintana is the team leader.
Jakob Fuglsang (Astana)
Jakob Fuglsang produced two stage wins to win his first WorldTour stage race. Source: Getty
Nationality: Danish
Age: 32
Notable grand tour results - Tour de France: 7th (2013)
Fuglsang gets mentioned here for his defeat of Porte and overall victory at the Criterium du Dauphine. A dogged domestique, his Dauphine win was his first pro win in five years.
The Danish rider will work for teammate Fabio Aru, but if the Italian falters, watch for him to strike out for a stage win and a top 10 placing overall regardless.
