Iga Swiatek was forced to retire from her Madrid Open clash with Ann Li on Saturday due to illness, sending the American 31st seed into the round of 16 of the WTA 1000 tournament.
A champion in the Spanish capital in 2024, Swiatek rebounded from a one-set deficit to level the contest but put an end to proceedings while down 0-3 in the decider.
The Polish six-time Grand Slam champion appeared to be struggling and asked for the doctor after getting broken early in the third set.
Following a conversation with the trainers, Swiatek tried to break Li back, but when her opponent held for a 3-0 advantage, the fourth seed realised she was unable to continue the match.
It is Swiatek's earliest ever exit in five appearances in Madrid.
Earlier in the day, 15th-seeded Iva Jovic squandered a lead and fell 3-6, 6-3, 6-2 to Canadian 24th seed Leylah Fernandez, who will be Li's opponent in the last 16.
Ninth-seeded Russian Mirra Andreeva overcame an inspired Dalma Galfi 6-3, 6-2 in a match that was much closer than the scoreline suggests.
'TRICKY MATCH'
The Hungarian qualifier ranked 117 in the world broke early in both sets but was unable to maintain her advantage as Andreeva recovered to improve her clay-court record this season to 9-1 and set up a last-16 showdown with another Hungarian, Anna Bondar.
"Today it was a very tricky match, Dalma is a very tricky opponent to play against," said Andreeva, who turns 19 on Wednesday.
"In the first set, I found myself on the back foot a little bit. She started well, hitting a lot of winners, being very solid and consistent. So I told myself that, 'If she wants to beat me to today, that's the level she has to play the whole match'. And I told myself, 'It's okay, even if now I don't feel like I'm playing my best, slowly I'll get there and figure out'.
"I'm just super happy that I won in straight sets today."
In ATP action, defending champion Casper Ruud raced into the third round with a 6-0, 6-1 demolition of home favourite Jaume Munar in just 65 minutes.
The 12th-seeded Ruud leads the ATP Tour in clay wins (133) and titles (12) since the start of the 2020 season and bids to become the third man to defend the Madrid crown after Rafael Nadal (2013-14) and Carlos Alcaraz (2022-23).