A 114 kilometre route in Aretxabaleta would prove a challenging one, with three classified climbs set to test the peloton.

The first two ascents in Spain caused the main field to reduce dramatically, but 40 riders would ultimately remain.

With 40km of racing to go, the leading group was split as 10 riders were able to pull clear.

Spain’s Ane Santesteban, Germany’s Clara Koppenburg and Sweden’s Emilia Fahlin were among the break, along with Pieters.

They proved able to stretch their advantage to over one minute, but still had two smaller climbs left to tackle.

Pauliena Rooijakkers sought to clinch a solo victory from the move, as the Dutch rider launched an attack from the group as the final 20km approached.

She proved unable to hold on as the chasing pack caught her in the final five kilometres, leaving the breakaway group readying themselves for a sprint to the line.

Pieters proved the fastest finisher, as the Boels Dolmans rider crossed the line in a winning time of 3 hours, 2min.

She was followed across the line by Fahlin and Koppenburg, who finished on the same time as the winner.

Rooijakkers would ultimately roll over the line four seconds down, alongside New Zealand’s Georgia Williams.

The main chase group, led by Germany’s Lisa Brennauer, crossed the line two minutes later.

The overall race leader Annemiek van Vleuten and Anna van der Breggen, both of The Netherlands, were part of the group.

Van Vleuten was able to narrowly hold on to her overall race lead, with the Mitchelton Scott rider now just two seconds clear of Williams.

Van der Breggen drops to third at 12 seconds off the lead.

The International Cycling Union Women's WorldTour race is set to conclude tomorrow.

The race will finish with a 50km stage in Iurreta.