The rivals had just begun the third set of their opening-round match when slippery conditions and the setting sun caused the match to be delayed to Tuesday.

The world No. 1 withdrew ahead of their match Friday with a fever and possible food poisoning.

The world No. 1 and Roland Garros champion had just reached her first career grass-court semifinal.

The WTA world No. 1 brushed aside Anna Blinkova, 6-3, 6-2, by breaking serve at love three times Thursday.

Making her first competitive appearance since winning the French Open, Swiatek claimed her eighth consecutive win and a tour-leading 36th of the season.

Second-seeded Liudmila Samsonova has eased into the second round of the Bad Homburg Open with a 6-1, 6-4 win over Viktoriya Tomova.

She is 8-3 in career finals but the Frenchwoman's last title was almost exactly three years ago in Nottingham in the buildup to 2019 Wimbledon.

"Unfortunately I woke up this morning with a blocked neck and this is not allowing me to perform to the best of my ability," wrote Halep.