Naomi Osaka suffers shock defeat at Birmingham Nature Valley Classic
World number one Naomi Osaka followed up her early French Open exit with a shock second-round loss to Kazakhstan's Yulia Putintseva in Birmingham.
The Japanese 21-year-old could lose her top ranking after losing 6-2 6-3.
Roland Garros champion Ashleigh Barty reached the quarter-finals and will overtake Osaka if she wins the title.
At the Mallorca Open, 2018 Wimbledon champion Angelique Kerber beat Maria Sharapova, who missed the clay-court season after having shoulder surgery.
The German 31-year-old defeated Sharapova, who has dropped to 85th in the world rankings, 6-2 6-3.
The tournament was 32-year-old Russian Sharapova's first since she withdrew from a second-round match at the St Petersburg Ladies Trophy in January.
Barty, 23, beat American Jennifer Brady 6-3 6-1 and is now close to taking the world number one ranking from US Open and Australian Open champion Osaka, who was beaten by unseeded Czech player Katerina Siniakova in the French Open third round.
Osaka would have stayed top if she had reached the final in Birmingham, but Barty now has the chance to become world number one for the first time.
"The stars have aligned a little bit for me and I think when you get those opportunities you have to do your best to take them with both hands," said Barty, who has now won nine matches in a row.
Five-time Wimbledon champion Venus Williams, 39, also reached the quarter-finals with a 6-3 6-2 win against Chinese sixth seed Wang Qiang.
The Birmingham Nature Valley Classic and Mallorca Open are grass-court tournaments which take place in the run-up to Wimbledon.