(Reuters) - Aryna Sabalenka and Ons Jabeur on Saturday became the latest top-10 players to retire from the Berlin Open due to injury or illness, after Wimbledon champions Elena Rybakina and Marketa Vondrousova also withdrew this week.
Sabalenka was forced to retire from her quarter-final against Russia's Anna Kalinskaya due to shoulder pain when the Belarusian trailed 5-1 in the opening set.
It marked the first time in her WTA Tour carer that Sabalenka had retired from a match because of injury.
Kalinskaya has reached the semi-finals with two walkovers after Wimbledon champion Vondrousova slipped and fell during their last-16 match, forcing the Czech player to retire.
Jabeur, meanwhile, was involved in a 72-minute opening set in her quarter-final with Coco Gauff which the American won 7-6(9) before the Tunisian retired because of illness.
Jabeur was seen getting her temperature checked before she retired.
"It doesn't feel like a win, especially because we had such a great first set. I wish Ons the best," Gauff said after reaching the semi-finals.
"I think it's something that's just going to happen today and she'll feel better tomorrow. I think she'll be strong at Wimbledon."
On Friday, Rybakina withdrew due to illness, sending Belarusian Victoria Azarenka through to the semi-finals. Rybakina was visibly struggling with what appeared to be abdominal pains.