10:50 CET - Play is set to get underway in 10 minutes, with Casper Ruud, Belinda Bencic and Leylah Fernandez first up.
You can follow the men's action here, and the women's here!
09:00 CET - Good morning and welcome back to our live coverage of the Madrid Open! The fourth round gets underway today on the women's side of the draw, while the last men's third-round matches will be completed.
Up first on the Manolo Santana Stadium at 11:00 CET, defending champion Casper Ruud has a tricky test against Spaniard Alejandro Davidovich Fokina.
That is followed by a heavyweight match-up that sees world number one, four-time Grand Slam champion and three-time Madrid winner, Aryna Sabalenka, clash with another four-time major victor, Naomi Osaka.
Coco Gauff, who was ill on court in her victory against Sorana Cirstea yesterday, then meets Linda Noskova.
Second seed Alexander Zverev begins the evening session against Terence Atmane, before world number two and Australian Open champion Elena Rybakina closes out the day against Anastasia Potapova.
There is plenty of action on the other courts, too, with the likes of Belinda Bencic, Mirra Andreeva, Marta Kostyuk, Daniil Medvedev and Felix Auger-Aliassime looking to book their spots in the next round.