Serena Williams took just 55 minutes to reach the second round of the US Open at the expense of fellow American Coco Vandeweghe.

The fourth seed, who beat Vandeweghe 7-5 6-3 in the final of this year's Stanford Open, was at her ruthlessly-efficient best.

She converted six out of seven break points and produced just nine unforced errors, prevailing 6-1 6-1 at Arthur Ashe Stadium.

Experienced Spaniard Maria Jose Martinez Sanchez, who overcame Mirjana Lucic in straight sets, will provide the opposition for Williams in round two.