(Reuters) - Fourth seed Angelique Kerber reached the Pan Pacific Open semi-finals in Japan on Friday after American Madison Keys retired due to injury early in the deciding set.
With the match clock at just over two hours, Kerber grabbed an early break to lead in the final set at 6-4 4-6 2-1, before Keys pulled out of the contest.
"It was a really good match in the first two sets, and this is never the way that you want to win the match," three-time Grand Slam winner Kerber said.
"I hope Madison will recover really soon so she is ready for the next tournaments."
After a run to the Eastbourne final in early July, Kerber won just one match at Wimbledon - where she was the holder - and arrived in Osaka on the back of a five-match losing streak.
The German expressed her delight at reaching her fifth Pan Pacific Open semi-final in six appearances since 2012.
"I think I like to play in Japan. Always when I'm coming back, I feel good here and I'm playing good tennis," former world number one Kerber said.
"This year, I'm here to play as good as I can and I'm looking forward to playing another semi-final here."
Persistent rain washed out the rest of the quarter-final matches, with home favourite Naomi Osaka's meeting with unseeded Yulia Putintseva moved to Saturday in the revised schedule.
The semi-final matches have been scheduled for the evening session, the organisers confirmed.
(Reporting by Hardik Vyas in Bengaluru, Editing by William Maclean)