(CNN) -- Portugal's Rui Costa rode to glory in Gap Tuesday as Tour de France leader Chris Froome was left fuming by a late high speed tangle with arch rival Alberto Contador.
Movistar rider Costa was part of a 26-strong breakaway group, who were allowed free reign on the 16th stage as Froome and the rest of the yellow jersey contenders waged their own private battle.
Costa, who was winning his second Tour stage, crossed the line after 168km from Vaison-la-Romaine to Gap in three hours 52 minutes 45 seconds.
He made a timely attack on the final second category climb of a testing day's racing to finish 42 seconds clear of second placed Christophe Riblon of France.
Britain's Froome came under repeated attack on the final ascent from Contador of Spain, but with help from Sky teammate Richie Porte, each was repulsed.
The final tricky descent into Gap saw Saxo Tinkoff's Contador make further attempts to claw back vital time on the race leader, but on a sharp corner, just over eight kilometers from the finish, he hit the tarmac.
Froome was also impeded and had to briefly take one foot out of his pedals, but was unscathed.
Porte then guided the pair back to the elite group, which also contained second-placed Bauke Mollema, Czech Roman Kreuziger and Nairo Quintana of Colombia.
Contador appeared to be examining injuries to his elbow, but rode freely to the finish.
He remained in third place overall, 11 seconds behind Mollema, but four minutes 25 seconds in arrears of the all-conquering Froome, who was clearly unimpressed by Contador's approach.
"It was bit careless of Contador," he told ITV Sport. "He overcooked one of the corners and came off in front of me.
"I just think at this stage of the race he is obviously getting desperate, attacking on the descents," he added.
The big loser on the day was Mollema's Belkin teammate Laurens Ten Dam, who was distanced by the late attacks and dropped out of the top five.
Dutchman Mollema was praised though for his sportmanship in refraining from making a further attack after Contador and Froome were held up by their incident.
Wednesday's 17th stage will give another clue as to the eventual winner of the centenary edition of the Tour -- a 32km mountain time trial from Embrun to Chorges in the Alps.
Froome, who extended his lead by winning Sunday's stage to Mont Ventoux, will be favored to take the honors as he bids to improve his second place on the 2012 Tour.