The Ag2R La Mondiale rider crossed the line in 17th place behind several of the big name contenders but it was enough to see him improve his overnight position by three places. He now trails the yellow jersey of Thomas Voeckler by four minutes and 47 seconds.
Voeckler successfully defended the maillot jeune on Bastille Day, but significantly, three-time champion Alberto Contador lost time to his overall rivals on the first mountain stage of this year’s race.
Sanchez finished ahead of Jelle Vanendert (Omega Pharma-Lotto) and Frank Schleck (Leopard Trek), who were second and third respectively, on a dramatic 211km 12th stage.
The overall favourites played a watchful role, but Frank Schleck’s move enhanced his position, while Contador (Saxo Bank-SunGard) struggled in the final stages, trailing in eighth, 43 seconds behind Sanchez.
It was a race within a race as Contador, Andy Schleck, Frank Schleck (both Leopard Trek) and Cadel Evans (BMC Racing) marked each other up the Tour’s first hors categorie (beyond category) climbs — the Col du Tourmalet and the ascent to Luz-Ardiden.
But Contador, who began the day 4:07 behind Voeckler (Europcar) saw his resistance broken in the final 500m of the last climb.
After an Andy Schleck attack and two from Frank Schleck, a third from the latter saw him break clear.
Frank Schleck closed in on Sanchez and Vanendert, while behind him Evans, Ivan Basso (Liquigas) and Andy Schleck continued to push at a high tempo, forcing Roche to just tail off the back on the approach to the finish.
Frank Schleck finished 10 seconds behind Sanchez and three behind Vanendert, while Basso was fourth, Evans fifth and Andy Schleck sixth, all three 30 seconds behind Sanchez — but crucially 13 seconds ahead of Contador.
Damiano Cunego (Lampre-ISD) was seventh, five seconds behind Basso’s group, before Contador crossed the line in eighth, followed by Voeckler in ninth.
Voeckler now leads overall from Frank Schleck by 1:49, with Evans third, 2:06 behind.
Andy Schleck lies fourth, 2:17 adrift, with Basso fifth at 3:16, Cunego sixth at 3:22 and Contador seventh, 4:00 adrift of Voeckler.
Today’s stage offers the riders a shorter and less hilly trek from Pau to Lourdes.