07:20 CET - It wasn't to be for Venus Williams overnight, with the 45-year-old losing 6-2, 6-2 to Magdalena Frech. Nevertheless, to win your first match back and then battle it out for over an hour in your second is a remarkable achievement in itself.
Women's top seed Jessica Pegula was also beaten, losing in three sets to Leylah Fernandez, but it wasn't all bad news for the home crowd with Taylor Fritz and Frances Tiafoe both picking up wins.
23:44 CET - Night is falling in Washington, and what a night it is set to be, with Jessica Pegula, Frances Tiafoe and Taylor Fritz all in action before Venus Williams continues her remarkable comeback.
Bring it on!
23:31 CET - An all-American clash has gone the way of world number 97 Taylor Townsend, who has crushed sixth seed Sofia Kenin 6-3 6-0 in just 57 minutes. That result will come as a surprise to many.
The final match of the day in Europe has been won by Damir Dzumhur, who has beaten Titouan Droguet 3-6, 7-5, 6-2 to move into the semi-finals in Umag.
23:09 - Fourth seed Ben Shelton has cruised through in Washington, claiming a 6-3, 6-2 win over Canadian talent Gabriel Diallo in just over an hour.
22:29 CET - In a fierce battle between the seventh and 11th seeds in the American capital, Alex De Minaur has beaten Jiri Lehecka 7-6, 6-7, 6-4 after two hours and 47 minutes.
Botic van de Zandschulp, meanwhile, has moved into the Kitzbuhel semi-finals with a 7-6, 6-2 win over Thiago Seyboth Wild.
21:22 CET - Lucky loser Corentin Moutet has moved into the Washington quarter-finals with a 6-2, 7-6 win over 2023 champion Dan Evans.
In Croatia, second seed Luciano Darderi has made the semis by beating home favourite Dino Prizmic 1-6, 6-2, 6-3.
20:37 CET - A clash between two US Open champions has been won by Emma Raducanu, who has beaten Naomi Osaka 6-4, 6-2 with a very impressive performance. The Brit looks to be getting back to her best.
20:22 CET - Alexander Bublik's winning run goes on! He's beaten compatriot Alexander Shevchenko 6-4, 6-2 in Kitzbuhel to secure his sixth victory in a row and move into the semis.
19:58 CET - 27-year-old Spaniard Carlos Taberner has secured a long-awaited first ATP semi-final of his career, beating Jesper de Jong 7-5, 6-3 to move into the final four in Umag.
19:26 CET - 14th seed Brandon Nakashima has advanced on home turf, beating Cameron Norrie 7-6, 6-3 in Washington.
18:27 CET - Daniil Medvedev continued a positive week in Washington after the disappointment of Wimbledon with a comfortable 6-3, 6-2 win against Yibing Wu.
17:17 CET - Top seed Linda Noskova was pushed by fellow Czech Katerina Siniakova, but ultimately had enough to get over the line and move into the Prague Open semi-finals with a 6-2, 4-6, 6-3 win.
15:18 CET - After reaching the Gstaad semi-finals last week, Arthur Cazaux is now into the last four in Kitzbuhel, easing past Jan-Lennard Struff 6-3, 6-4.
14:56 CET - Fifth seed Marie Bouzkova is into the last four in Prague, with the Czech fighting from a set down to clinch a 3-6, 6-3, 6-3 victory over American Ann Li.
13:30 CET - Arthur Rinderknech has moved into the Kitzbuhel semi-finals, with the sixth seed battling to a 6-4, 3-6, 6-1 win over Yannick Hanfmann.
12:41 CET - Tereza Valentova is the first winner of the day in Prague, with the 18-year-old obliterating Jessika Ponchet 6-2, 6-0 in just over an hour to soar into the last four on home turf. It is the teen's first semi-final appearance on the WTA Tour!
09:48 CET - In Kitzbuhel, top seed Alexander Bublik will be looking to continue his fine run of form and win titles in back-to-back weeks. He takes on fellow Kakazh Alexander Shevchenko at around 14:00 CET, with play getting underway in Austria at 11:00 CET.
The last eight in Umag gets going at 16:30 CET, with second seed Luciano Darderi also targeting the same feat as Bublik after clinching the Bastad crown just last week. He will be the favourite against Dino Prizmic later this evening.
In the Livesport Prague Open, top seed Linda Noskova will try to continue her march to success on home soil when she comes up against fellow Czech and 11-time doubles Grand Slam champion Katerina Siniakova at 14:00 CET. Play gets underway in a couple of hours.
And finally, the main event starts at 17:00 CET in Washington, where several stars are eyeing quarter-final spots. Daniil Medvedev gets play going, before Alex de Minaur, Ben Shelton, Frances Tiafoe and Taylor Fritz all take to the court.
On the women's side, Emma Raducanu faces Naomi Osaka in a really intriguing encounter between Grand Slam champions, while Sofia Kenin and Jessica Pegula also headline events. But of course, the player everyone is waiting for is Venus Williams, who will be aiming to back up her staggering opening round win at the age of 45 against Magdalena Frech. Surely she can't do it again...
08:45 CET - Hello and welcome back to a big week of action as tournaments around the world start to reach the business end.