Stage one winner Philippe Gilbert (Omega Pharma-Lotto) was second, 12 seconds behind after a late burst, with Cadel Evans (BMC Racing) third.

Evans’ sprint to the line in a bid to assume the maillot jaune from Hushovd was in vain as the Garmin-Cervelo rider finished in the same group, 15 seconds behind Hushovd.

The overall contenders began to show themselves, with defending champion Alberto Contador (Saxo Bank-SunGard) marked closely by two-time runner-up Andy Schleck (Leopard Trek).

Contador finished eighth, with Schleck ninth, both claiming the same time as 2007 and 2008 runner-up Evans.

Team Sky's Xabier Zandio was in the day's nine-man break, which began after nine kilometres.

The Spaniard was accompanied by Costa, Christophe Riblon (Ag2r La Mondiale), Addy Engels (QuickStep), Julien El Fares, Romain Zingle (both Cofidis), Tejay van Garderen (HTC-Highroad), Alexandr Kolobnev (Katusha) and Cyril Gautier (Europcar).

The group had an advantage of more than four minutes with 50km remaining.

Van Garderen accelerated up the day’s category two ascent of the Col de la Croix Saint-Robert to stretch the escape.

The HTC-Highroad rider reached the top, the 25km-to-go mark, first, with only three of his fellow breakaway riders for company – Riblon, Gautier and Costa.

Alexandre Vinokourov, who began the day 10 seconds behind Hushovd, and his Astana team-mate Paolo Tiralongo attempted to bridge the gap, while Johnny Hoogerland (Vaconsoleil), wearing the King of the Mountains’ polka dot jersey, also attacked the peloton, with Juan Antonio Flecha (Team Sky) in pursuit.

Hoogerland’s break did not last, but Flecha latched onto Vinokourov and Tiralongo.

Vinokourov forged forward, reducing the deficit to the front quartet with every revolution of his pedals, but still Flecha held on.

Out in front Van Garderen responded to an attack from Riblon, but the leading quartet stayed together.

The weather closed in and the rain began to fall as the final summit to Super-Besse Sancy began and Costa went clear alone, Van Garderen, Riblon and Gautier losing touch with the Portuguese climber.

Vinokourov powered on and had Costa in his sights at 1km to go.

However, the peloton, having absorbed the remaining breakaway riders, were also closing fast, with the overall contenders coming to the fore.

Schleck was watching every move made by Contador, as was Evans.

Gilbert was also prominent and attacked inside the final kilometre, powering past Vinokourov, who was suffering.

Costa, though, had enough of a cushion to claim victory ahead of Gilbert, with Evans finishing fast in third place.

However, Hushovd was strong in the finale, finishing in a 21-strong group behind Evans to retain the maillot jaune for another day.

Ireland's Nicolas Roche was also among that group and moves up to 14th in General Classification.