The 186 kilometre stage was expected to conclude in a bunch sprint, with the day offering one of few chances for sprinters to clinch victory at the Spanish Grand Tour.

Belgium’s Wallays aimed to defy the expectation, featuring in a three-man breakaway group with the Netherlands’ Jetse Bol and Norway’s Sven Erik Bystrøm.

The trio attacked early in the stage and were able to build a lead which peaked at just over 2min 30sec.

Their advantage largely remained at the two minute mark, but it began to fall in the closing 20 kilometres as the peloton increased the pace.

While Bol was ultimately dropped from the breakaway in the closing 10km, Wallays and Bystrøm succeeded in remaining out front until the closing kilometres.

Slovakia’s three-time world champion Peter Sagan attempted a long sprint to close the gap.

It proved too late as Wallays was able to kick clear of Bol to take the stage win in a time of 3hr 57min 3sec.

Bol ended as the runner-up, with Sagan leading the peloton over across the line on the same time as the leading duo.

“Everybody was expecting a bunch sprint,” said Wallays, who rides for Lotto Soudal.

“I knew that if I was feeling good I could surprise many riders and today I did it.

“With a 25 second gap with two kilometres to go, I stayed in the wheel.

“I waited, I waited.

“I wasn’t scared to lose, I was already happy to put on a show until the last kilometre.

“Everyone expected a massive sprint so if you see the breakaway still at the front it’s exciting.

“I worked very hard to be selected for the Tour de France.

“I didn’t go there and then I worked for a stage win at La Vuelta and I get it, it’s fantastic.”

The stage provided rare respite for the general classification contenders in the battle for the overall title.

Britain’s Simon Yates remains in the overall lead, with a 25 second advantage over second place Alejandro Valverde of Spain.

They will resume their head-to-head duel tomorrow with a 154km mountain stage in Andorra.