By Nigel Wynn
Chris Froome (Sky) lost the overall race lead in Tirreno-Adriatico after Vincenzo Nibali (Astana) distanced the British rider on a wet, twisting descent on the run-in to the finish in Porto Sant'Elpidio.
Super-strong Peter Sagan (Cannondale) easily won the stage from a lead trio containing Nibali and Joaquim Rodriguez (Katusha).
Froome now faces a tough battle in tomorrow's final time trial to claw back Nibali's 34 second time advantage and to keep Alberto Contador (Saxo-Tinkoff) at bay. But looking further ahead to the Grand Tours, Nibali now has solid confirmation where Froome's weakness lies - on the descents. It's the first time this seaon that Froome and Sky have looked vulnerable.
How it happened
Although the big mountain stages may have been over, the penultimate stage offered up a tough parcours with a sawtooth profile packing in numerous short, steep climbs - a proper warm-up for the classics riders.
A 15-man escape group had been away earlier in the stage, but several riders found the pace too hot and fell back - surprisingly including Fabian Cancellara (RadioShack-Leopard). That eventually left seven main protagonists: Damiano Cunego (Lampre-Merida), Tom Dumoulin (Argos-Shimano), Daryl Impey (Orica-GreenEdge), Benat Intxausti (Movistar), Egoi Martinez (Euskaltel-Euskadi), Mirko Selvaggi (Vacansoleil-DCM) and Giovanni Visconti (Movistar).
The chasing peloton was at first led by the Sky squad of overall leader Froome, but switched to Cannondale in the final 30km eager to set up the race for their man Sagan.
With the catch imminent, Omega Pharma-QuickStep also joined the pace-setting of the bunch, and the advantage of the break was soon whittled away. Dumoulin kicked out for a solo move with 20 kilometres to go for a last-ditch attempt to keep the bunch at bay. Intxausti first bridged up to Dumoulin on the final climb, and then rode away from him on the descent as the rain started to pour.
Nibali saw his chance to attack the bunch on the tight descent with Samuel Sanchez (Euskaltel-Euskadi) in pursuit.
Nibali's superior descending skills saw him quickly catch Intxausti, and then Sanchez and Sagan joined them to briefly form a lead quartet. Nibali and Sagan then rode clear and were joined by Rodriguez. Meanwhile, Contador had worked his way into the chasing group but Froome found himself dangerously distanced from his rivals and had to work solo to link up with a second chase group. The effort took its toll.
Nibali, Sagan and Rodriguez worked together well and built up a minute's lead over Froome's group and half a minute over Contador.
By the finish, Nibali and Rodriguez seemed happy to let Sagan have another stage win - or unable to stop him - safe in the knowledge that they would move up the overall classification.
The day's exhausting riding was too much for many riders with some big names pulling over to the side of the road and heading back to the team hotel. Andy Schleck (RadioShack-Leopard) was one of the highest profile drop-outs, and it marks yet another race this season that the Luxembourger has failed to finish. Mark Cavendish (Omega Pharma-QuickStep) also withdrew during the stage along with over 50 other riders.
American Taylor Phinney (BMC Racing) got dropped by the grupetto but carried on alone, finishing the stage but cruelly outside the time limit.
The race is far from over. Tomorrow, the riders remaining in the race will face a 9.2-kilometre individual time trial. Watch out for both Froome and British time trial ace Alex Dowsett looking to take his first victory for his new team, Movistar.
Tirreno-Adriatico 2013, stage six: Porto Sant'Elpidio to Porto Sant'Elpidio, 209 km
1. Peter Sagan (Svk) Cannondale in 5-45-17
2. Vincenzo Nibali (Ita) Astana at 2 secs
3. Joaquin Rodriguez (Spa) Katusha at same time
4. Mauro Santambrogio (Ita) Vini Fantini-Selle Italia at 44 secs
5. Samuel Sanchez Spa) Euskaltel-Euskadi at st
6. Christopher Horner (USA) RadioShack-Leopard at st
7. Alberto Contador (Spa) Saxo-Tinkoff at st
8. Jurgen Roelandts (Bel) Lotto Belisol at 50 secs
9. Thor Hushovd (Nor) BMC Racing at st
10. Simon Geschke (Ger) Argos-Shimano at st
Overall classification after stage six
1. Vincenzo Nibali (Ita) Astana
2. Christopher Froome (GBr) Sky at 34 secs
3. Joaquin Rodriguez (Spa) Katusha) at 37 secs
4. Alberto Contador (Spa) Saxo-Tinkoff at 48 secs
5. Michal Kwiatkowski (Pol) Omega Pharma-QuickStep at 58 secs
Many riders founds themselves over-geared and unable to ride up some of the climbs
Peter Sagan continues to impress with another win
Vincenzo Nibali takes the race lead
Tirreno-Adriatico 2013: Coverage index
Tirreno-Adriatico 2013: Race preview and information
Tirreno-Adriatico 2013: Start list
Tirreno-Adriatico 2013: Who will win?
Tirreno-Adriatico 2013: The Big Preview
Tirreno-Adriatico 2013: Stage reports
Froome takes Tirreno lead
Stage four: Froome wins; Kwiatkowski leads
Stage three: Sagan beats Cavendish and Greipel
Stage two: Goss wins on wet stageStage one: Mark Cavendish leads Tirreno with team time trial win
Tirreno-Adriatico 2013: Photo galleries
Stage six photo gallery
Stage two photo gallery
Stage one TTT photo gallery
Read more at http://www.cyclingweekly.com/news/latest/537230/tirreno-adriatico-2013-coverage-index.html#4dzuo2fK4puRQhVp.99