Chris Froome’s bid for a fifth Tour de France title looks over after he finally cracked on stage 17 and saw teammate Geraint Thomas add to his healthy race lead.

Froome simply could not go with Thomas on a gruelling 65km stage from Bagneres-de-Luchon to Saint-Lary-Soulan that featured three major climbs, with the defending champion now two minutes and 31 seconds adrift of Thomas.

The Welshman’s main rival is Sunweb’s Tom Dumoulin, who is one minute and 59 seconds behind, and with just four stages remaining, Froome acknowledged he would now be playing a supporting role to Thomas.

The surprise came on the same day as Movistar’s Nairo Quintana beat UAE Team Emirates’ Dan Martin for stage victory.

“I just didn’t have the legs in the final [stages],” Froome said afterwards.

“It was a very intense day but I’ve got no regrets. G [Geraint] has ridden such an amazing race and he deserves to be in yellow.

“Fingers crossed, he holds it now until Paris.

“That’s professional cycling. That’s what a team is all about. I’m happy just to be in this position.

“I’ve won the last three grand tours I’ve done now, so it’s certainly been tough build-up for me but I’m still going to try and fight for the podium and try to keep G up there in yellow.”

Froome’s day was summed up when it emerged that he was tackled by police when riding back to the Team Sky bus once the stage was complete.

Officers assumed Froome was a fan because of a rain jacket he was wearing and although he was unharmed, he did crash his bike in the confusion.

Thomas had predicted Wednesday’s action would be “massively decisive” as questions remained on his ability to go with the race’s best climbers.

But the Team Sky rider thrived on a brutal day and when asked if he was now the team’s main man, Thomas modestly said: “I guess so”.

“I think that I’m in a good position now,” he added.

“With four kilometres to go, Froome was on the radio and said that he wasn’t feeling super. That gave me confidence because if Froome is suffering then everyone is suffering, and I was feeling good.

“I didn’t want him to have a bad day like he did but it gave me confidence that someone [of] his stature was struggling.”

Significant hype surrounded stage 17, the shortest on the Tour for 30 years, and Astana’s Tanel Kangert and AG2R-La Mondiale’s Pierre Latour made early moves.

Stage 16 winner Julian Alaphilippe was in the mix, too, but riders struggled to put a decent gap on the top general classification contenders.

Quintana, who earlier in the day had to change his bike, then made his mark, seeing off Polish rider Rafal Majka before also leaving Kangert in his dust.

Quintana celebrates his stage victory. Photo: Getty

The real battle was going on a bit further back, though, as Froome lost his way in the final kilometres, allowing Thomas to gain significant time on his race rival.

And the race leader crossed the line in third, a tremendous result given the nature of the stage.

“I think he’s got [it] almost. What is it? A two-minute lead on Dumoulin? Which is, I think, a pretty comfortable buffer,” Froome said of Thomas’ victory chances.

“He looks really strong so I imagine he’ll be able to finish it off. We’ve just got to try and look after him now, these next few days.”

With a time trial to come – and the fact Dumoulin is a world time-trial champion – Thomas was not getting carried away.

“I’m not going to change my mental approach and I’m just going to go day-by-day, try and recover as best as possible and do the small things right,” he said.

“I’ll worry about tomorrow because as soon as you take your eye off the ball or get carried away, that’s when it goes downhill.”

Also on Thursday morning (AEST), Slovakian Peter Sagan, who crashed during the stage but managed to finish, moved to assure fans he would complete the race.

Sagan just needs to finish to win the green sprinters jersey for a sixth time.

Stage 18 is a flat one, with riders racing from Trie-sur-Baise to Pau over 171 kilometres.

Stage 17 results

1. Nairo Quintana (Movistar) 2 hrs 21 mins 27 secs
2. Dan Martin (UAE Team Emirates) + 28 secs
3. Geraint Thomas (Team Sky) + 47 secs
4. Primoz Roglic (LottoNL-Jumbo) + 52 secs
5. Tom Dumoulin (Sunweb) same time
6. Steven Kruijswijk (LottoNL-Jumbo) + 1 min 5 secs
7. Egan Bernal (Team Sky) + 1 min 33 secs
8. Chris Froome (Team Sky) + 1 min 35 secs
9. Mikel Landa (Movistar) same time
10. Ilner Zakarin (Katusha-Alpecin) + 2 mins 1 sec

General classification standings

1. Geraint Thomas (Team Sky) 70 hrs 34 mins 11 secs
2. Tom Dumoulin (Sunweb) + 1 min 59 secs
3. Chris Froome (Team Sky) + 2 mins 31 secs
4. Primoz Roglic (LottoNL-Jumbo) + 2 mins 47 secs
5. Nairo Quintana (Movistar) + 3 mins 30 secs
6. Steven Kruijswijk (LottoNL-Jumbo) + 4 mins 19 secs
7. Mikel Landa (Movistar) + 4 mins 34 secs
8. Romain Bardet (AG2R La Mondiale) + 5 mins 13 secs
9. Dan Martin (UAE Team Emirates) + 6 mins 33 secs
10. Jakob Fuglsang (Astana) + 9 mins 31 secs