GAP, France -- Hurtling too fast for comfort down a twisty, turning foothill of the Alps, Tour de France leader Chris Froome faced a high-speed choice between risk and reward.

The Briton knew that 10 years ago on exactly the same descent, Joseba Beloki shattered his leg, elbow and wrist rounding a corner too fast and Lance Armstrong plowed into a field to avoid the prone Spaniard howling in pain.

So Froome wanted to go easy. Trouble was, Alberto Contador didn't. Against his better instincts, Froome chased after his Spanish rival who sped down the treacherous stretch with asphalt made gooey and slippery by the July heat.

Just like Armstrong, flirting with disaster nearly cost Froome the Tour. Contador crashed as he rounded a right-hand corner, forcing Froome to swerve off the road, onto the grass and to put a foot down to stay upright.

Unlike Contador, who bloodied his right knee, Froome escaped with just a fright. Still, the drama on Tuesday's Stage 16 proved a point that Froome and his Sky team have made time and again: Despite his big lead, Froome won't savor victory until he's on the cobbles of the Champs-Elysees in Paris on Sunday.

"One second you could be going for the finish and about to win a race and the next you're lying in a ditch somewhere, with a broken bone," Froome said.

"I knew it was the descent where Beloki crashed so I was purposefully laying off a little bit and trying to take it easy but at the same time also trying to keep touch with the Saxobank guys who were really pushing the limits."

By that, Froome meant Contador and his Saxo-Tinkoff teammate from the Czech Republic, Roman Kreuziger, who are third and fourth in the overall standings but more than four minutes off the lead.

Opportunities for them to claw back are fast running out. The finish line in Paris is now just 415 miles and five days away. To their credit, they aren't simply accepting defeat but are harassing Froome all the way. If Froome wins, the way his rivals have repeatedly tested the British rider over the three weeks should give him the extra satisfaction of a victory hard-earned.

Bauke Mollema remains second overall, 4:14 behind Froome, while Contador remains 4:25 back in third.

Portuguese rider Rui Costa won Stage 16 with a solo breakaway.

To cool the asphalt, authorities doused the top of the climb with water. But Froome wingman Richie Porte said the road down from there was sticky and slippery -- just as it was in the heat wave of 2003, when Beloki's back wheel slid away from him on a bend, hurling him to the ground. Armstrong went on to win that race but had all seven of his Tour titles stripped for doping.