break point

World number one Sabalenka disagreed with an "out" call on her shot when she was break point down against Mertens.

Had it not been overruled, Kartal would have had a break point.

Mensik did not face a break point in the second set and the heat and humidity began to take a toll on Djokovic.

The only blip for the 13th seed came when he served for the match at 5-2, relinquishing his double break advantage with a double fault on break point.

Djokovic's return of serve - one of the hallmarks of his unparalleled success - was particularly poor against Van de Zandschulp, who swamped the Serb's second serve to convert five of eight break point opportunities.