Chris Froome was seething with defending champion Vincenzo Nibali as the Tour de France leader set up a duel for overall victory up Alpe-d'Huez with Nairo Quintana.
Nibali (Astana) was determined to rescue some consolation from his title defence ending poorly and surged to victory on yesterday's 138-kilometre 19th stage from Saint-Jean-de-Maurienne to La Toussuire.
Froome felt the Italian's initial acceleration was exploiting the Team Sky leader's mechanical problem, but Froome fought back and limited the damage on the concluding climb to Quintana (Movistar).
Nibali won by 44 seconds from the Colombian, with Froome one minute 14 seconds adrift to take a lead of 2:38 into today's final stage in the Alps. The race finishes in Paris tomorrow.
The history between Froome and Nibali - the pair had a heated discussion on the Astana team bus after stage six to Le Havre as the Italian erroneously felt Froome was culpable for a crash - darkened as the pair had a finish-line exchange.
"I told him exactly what I thought of him," Froome said.
"I felt very specifically the moment he attacked in the mountains today it was almost as if my mechanical provoked his attack.
"A piece of asphalt or small stone got stuck between my brake calipers and my rear wheel. The rear wheel just jammed up. I had to stop and get it out before I could continue.
"I've heard from other riders that he turned, could see I had a mechanical and then attacked.
"In my opinion it's very unsportsmanlike, it's not in the spirit of the Tour de France and it's definitely not what this race is about."
Now only Quintana and the 110.5km 20th stage which finishes atop Alpe-d'Huez stands in the way of Froome and a second yellow jersey.
La Toussuire was the scene of Froome's attack on Team Sky leader Bradley Wiggins in the 2012 Tour, but now Froome is the undisputed leader.
The concluding 18km ascent was always where the race would ignite and so it proved as Quintana attacked with 6km remaining.
Froome was the only rider who could keep pace as Alberto Contador (Tinkoff-Saxo) and Alejandro Valverde (Movistar) slipped behind.
The Colombian climber made gains on Froome but will need to attack earlier to seize the maillot jaune in dramatic fashion today.