Gritty Frank clinches 17th stage

The Spaniard spoiled the brothers' party by sticking with them in the last two of five climbs on the final stage in the Alps, strengthening his overall lead with four days left in the race.

"Alberto has now won the Tour," his Astana team chief Alain Gallopin told reporters on the finish line.

The ceaseless efforts of the two riders from Luxembourg were not entirely vain as Frank won the stage ahead of Contador and the brothers secured places on the podium before a potentially decisive time trial in Annecy.

Andy Schleck is now second overall, two minutes 26 seconds behind 2007 champion Contador and Frank is third, 3:25 adrift. Frank Schleck dedicated the stage victory to his German team-mate Jens Voigt, who crashed on the previous stage and was forced out of the Tour with a broken cheekbone.

If Contador resisted their repeated strikes on the demanding Col de Romme, climbed for the first time on the Tour, and the final Col de la Colombiere, it was not the case for two other contenders, Lance Armstrong and Briton Bradley Wiggins.

Dropped in the steep penultimate hill, Armstrong fought back bravely on the last descent, finishing fifth with Italian Vincenzo Nibali and crossing the line 2:18 behind the leading trio.

But it was not enough for him to remain in the medal spots and the seven-times champions slipped to fourth overall, 3:55 behind his Astana team leader.

The Briton limited the damage, finishing seventh 3:07 behind Frank Schleck and dropped to sixth overall, 4:53 off the pace. Contador said he felt the Olympic pursuit champion's failure was his best gain of the day. The race leader warned that if two brothers on the podium was an extraordinary feat, the Tour could produce another unprecedented achievement with three riders from the same team in the top three in Paris.

Norwegian Thor Hushovd had stolen the show in the first half of the stage, parting company with the rest of the bunch in the Col des Saisies to strengthen his hold on the green jersey.

His break allowed him to collect points along the way and secure un unassailable 30-point lead over Briton Mark Cavendish in the points standings.