Alison Riske of the US returns to Roberta Vinci of Italy in their first round match of the Wimbledon Championships at the All England Lawn Tennis Club, in London, Britain, 28 June 2016. EPA/HANNAH MCKAY

Amra Sadikovic of Switzerland returns to Serena Williams of the USA during their first round match at Wimbledon Championships at the All England Lawn Tennis Club, in London, Britain, 28 June 2016 EPA/ANDY RAIN

Andrea Petkovic of Germany returns to Nao Hibino of Japan during their first round match of the Wimbledon Championships at the All England Lawn Tennis Club, in London, Britain, 28 June 2016. EPA/GERRY PENNY

Caroline Wozniacki of Denmark returns to Svetlana Kuznetsova of Russia during their first round match at the Wimbledon Championships at the All England Lawn Tennis Club, in London, Britain, 28 June 2016 EPA/ANDY RAIN

Johanna Konta of Britain celebrates a set point winner against Monica Puig of Puero Rico during their first round match of the Wimbledon Championships at the All England Lawn Tennis Club, in London, Britain, 28 June 2016. EPA/FACUNDO ARRIZABALAGA