Charleston, SC, USA, 7 April 2017 | AAP

Sam Stosur, Daria Gavrilova and Anastasia Rodionova have all been knocked out in the third round of the Volvo Car Open in Charleston, South Carolina.

Sixth seed Stosur hit 24 unforced errors in a 7-5 6-3 loss to Romanian world No.33 Irina-Camelia Begu played in windy conditions.

Begu sent down five aces to Stosur’s one in the opening set before breaking the 2011 US Open winner twice in the second to coast to a straight-sets victory.

World No.27 Gavrilova went down to close friend and doubles partner, Russian Daria Kasatkina, 6-3 4-6 6-0.

Both players struggled to find a rhythm on serve in a see-sawing opening two sets – but the unseeded Kasatkina lifted in the deciding set to save all four of Gavrilova’s break points.

Qualifier Anastasia Rodionova’s winning run came to an end against fifth seed Caroline Wozniacki 6-3 6-3.