TOUR DE FRANCE (5-27 July) BBC coverage: Daily text commentary, reports and gallery on the BBC Sport website and live audio commentary from BBC Radio 5 Live
Kirchen is the first Luxembourger to wear the yellow jersey in 50 years
Italian Riccardo Ricco won stage six of the Tour de France as Kim Kirchen snatched the yellow jersey in the first significant climb of the race.
Kirchen finished the 195.5km stage in fifth place, usurping Stefan Schumacher at the top of the overall standings.
Schumacher's hopes of retaining the leader's jersey were wrecked after a crash inside the final kilometre.
Kirchen has an overall six-second lead over Cadel Evans, who finished third, while David Millar drops to fifth.
The victory was the Saunier Duval-Scott rider's first Tour stage win, timing his attack in the closing stages of the category two finish at Super-Besse in a time of four hours, 57 minutes and 52 seconds.
"I wanted to win a stage and I achieved my goal as early as the sixth stage," said the 24-year-old, who finished second in the Giro d'Italia to Alberto Contador in June. "Now I'll take the race day by day."
Kirchen became the first cyclist from Luxembourg to wear the yellow jersey since Charly Gaul in 1958.
And the Team Columbia rider believes a good performance in the mountains will see him well poised when the Tour rolls into the French capital.
"The Tour is the Tour and there are still a lot of days ahead of us but my form is really exceptional," said the 30-year-old, who finished seventh in last year's race.
"If I avoid losing too much time in the Pyrenees, I can tell you I'll be near the front in the Alps and perhaps in Paris as well."
Alejandro Valverde also remains in contention in the overall picture after finishing just behind Ricco in an enthralling stage as the Tour moved into the mountains for the first time.
Once again a French trio took the early initiative as Sylvain Chavanel, Benoit Vaugrenard and Freddy Bichot broke away in the opening 15km.
At one stage the three riders had opened up a five-minute gap on the peloton as they searched for valuable bonus points on offer.
Chavanel managed to capture the polka dot King of the Mountains jersey when he conquered the 1401m Croix-Morand pass at 158kms, moving him to 23 points alongside compatriot Thomas Voeckler.
But the Cofidis rider was caught 12kms from the finish line as the yellow jersey of Schumacher and the leading contenders lined up for a frantic finish.
The Gerolsteiner rider had looked to have done enough to keep the jersey for a second stage as he trailed Kirchen in the final kilometre of the climb.
But Schumacher collided with team-mate Bernard Kohl at the worst time possible, handing Kirchen the opportunity to sprint for the yellow jersey.
"It was one of those things - it wasn't deliberate," said the German, who drops to third in the general classification.
David Millar lost time on the leaders after finishing in 39th place, 51 seconds behind Ricco.
The Garmin-Chipotle rider - who had began the day in third place and with high hopes of challenging for the maillot jaune - drops down to fifth place overall behind team-mate Christian Vandevelde.
Meanwhile Wednesday's stage five winner Mark Cavendish struggled on the two category two and two category four climbs, crossing the finishing line in 168th place.
Stage six results:
1. Riccardo Ricco (Italy/Saunier Duval-Scott) 4 hours, 57 minutes, 52 seconds. 2. Alejandro Valverde (Spain/Caisse d'Epargne) +1 second 3. Cadel Evans (Australia/Silence-Lotto) same time 4. Frank Schleck (Luxembourg/CSC-Saxo Bank +4 seconds 5. Kim Kirchen (Luxembourg/Team Columbia) same time 6. Roman Kreuziger (Czech Republic/Liquigas) +7 secs 7. Moises Duenas (Spain/Barloworld) same time 8. Carlos Sastre (Spain/CSC Saxo Bank) same time 9. Denis Menchov (Russia/Rabobank) same time 10. Leonardo Piepoli (Italy/Saunier Duval-Scott) same time
39 David Millar (Britain/Garmin-Chipotle) +51 secs 168 Mark Cavendish (Britain/Team Columbia) + 17 minutes 46 seconds
Overall standings (after six stages):
1. Kim Kirchen (Luxembourg/Team Columbia) 24 hours, 30 minutes, 41 seconds 2. Cadel Evans (Australia/Silence-Lotto) +6 3. Stefan Schumacher (Germany/Gerolsteiner) +16 4. Christian Vande Velde (USA/Garmin-Chipotle) +44 5. David Millar (Britain/Garmin-Chipotle) +47 6. Thomas Lovkvist (Swden/Team Columbia) +54 7. Denis Menchov (Russia/Rabobank) +1:03. 8. Alejandro Valverde (Spain/Caisse d'Epargne) +1:12. 9. Stijn Devolder (Belgium/Quickstep) +1:21. 10. Oscar Pereiro (Spain/Caisse d'Epargne) +1:21.
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