A six-man breakaway group had been allowed to move clear of the main field after 80 kilometres of the stage of the International Cycling Union (UCI) WorldTour race, as they tackled several tough climbs, including the second category Alto de Aia.

The final ascent of the climb at 13 kilometres until the finish provided a launchpad for Spain’s Alberto Contador and the Colombian duo of Sergio Henao and Volta a Catalunya winner Nairo Quintana to attempt an attack.

Spain’s Carlos Verona, the final breakaway rider, was eventually caught as the stage entered the closing three kilometres, with the overall contenders preparing to attack the faltering race leader Mikel Landa.

The Spaniard was among a host of the favourites to fail to follow Sanchez’s move in the final kilometre, with the Beijing 2008 Olympic road race champion attacking on a climb to move clear to the finish.

Sanchez eventually held off the closing pack to cross the line in a winning time of four hours, 13min and 12sec to claim his first individual victory since 2013.

Portugal’s Rui Costa, the 2013 world champion, finished on the same time as the stage winner to finish in second place, with France’s Warren Barguil taking third.

After ending the stage eight seconds adrift of the winner, Landa saw his leadership of the race draw to a close.

LottoNL-Jumbo’s Kelderman, who had been one second off the pace at the start of the day, now leads the standings by four seconds from Team Sky’s Henao.

Tinkoff’s Contador could still pose a threat in the final two days of racing, with the Spaniard lying fifth, 10 seconds behind Kelderman.

The penultimate stage of the race – also known as the Tour of the Basque Country – will see the peleoton tackle a 159km mountain stage from Orio to Eibar.