23:56 CET - Cleveland third seed Katerina Siniakova (28) is through to the next round after a fightback win over Jessica Bouzas Maneiro (21), winning her game 2-6, 6-4, 7-6.
22:32 CET - Over to Cleveland, where it was an easier ride for Beatriz Haddad Maia (28) with the Brazilian top seed overcoming Cristina Busca (26) 6-2, 6-1.
22:21 CET - Winston-Salem's 15th seed Pavel Kotov (25) had to fight for his win over Zachary Svajda (21), but he downed the American in three sets 3-6, 6-3, 6-4 to make his way into the last eight.
21:45 CET - Our first result of the day from the Winston-Salem is in with Belgium's David Goffin (33) advancing past Frenchman Arthur Rinderknech (29) in straight sets 6-3, 6-3.
20:46 CET - We have our next result from Cleveland where fifth seed Anastasia Potapova (23) is through to the next round with a 6-2, 6-2 victory over Clara Tauson (21).
19:22 CET - The first two matches of the day in Cleveland have seen two seeded players crash out, with seventh seed Viktoriya Tomova (29) losing 6-3, 6-3 to Arantxa Rus (33) and fourth seed Xinyu Wang (22) being beaten 3-6, 6-4, 6-2 by McCartney Kessler (25).
18:47 CET - Former Wimbledon champion Marketa Vondrousova (25) has undergone shoulder surgery days after she withdrew from this month's US Open due to injury.
15:06 CET - Today's action will get underway in just under two hours, with two WTA clashes in Cleveland getting the ball rolling. Three hours after that, ATP action in Winston-Salem will begin.
Looking further ahead, those in action tonight include Borna Coric (27), Beatriz Haddad Maia (28) and Sofia Kenin (25).
10:35 CET - The biggest story in the world of tennis this week is the fact that world number one Jannik Sinner (23) has been cleared of fault or negligence by an independent tribunal after failing two drug tests in March, and many players feel it's unfair that he hasn't been handed a ban.
08:55 CET - The day has started with an upset, with top seed Danielle Collins (30) losing 1-6, 6-3, 6-3 to world number 89 Erika Andreeva (20) in Monterrey. That's not the preparation the American would have wanted for what will be her final Grand Slam before retirement.
08:24 CET - Hello and welcome to Flashscore's coverage of today's tennis!