04:40 CET - It took the number one seed Tommy Paul two and a half hours, but he comes from a set down to beat Cristian Garin 2-6, 6-2, 7-6 (5). Despite hitting 47 unforced errors throughout the match, the American held on to advance. He was broken when serving for the match at 5-4 in the decider, but recovered in the tiebreak.
04:00 CET - The number 13 seed Elise Mertens defeats Varvara Gracheva 6-3, 7-5 to progress to the quarter-finals in Charleston. There were a total of nine breaks of serve as neither player served very well throughout the contest. In the end, the Belgian held her nerve to move on.
01:35 CET - Qinwen Zheng marches on in Charleston as she dismesses Maria Sakkari 6-4, 6-1. The Chinese number one saved both of the break points she faced, while converting four of her eight opportunities. Next for Zheng will be either Gracheva or Mertens.
01:30 CET - In a battle of Americans, Colton Smith got the better of Ethan Quinn 6-3, 6-4 to move on. Winning an impressive 87% of his first service points, Smith was not broken in the match. He will face either Paul or Garin in the quarter-finals.
00:05 CET - American Jenson Brooksby has caused a huge upset in Houston to knock out third seed Alejandro Tabilo, winning a three-set thriller 3-6, 6-4, 7-6 (8-6).
23:22 CET - Ajla Tomljanovic and Ashlyn Krueger are the next women through in Charleston, with both players claiming straight set wins to move into the last 16.
21:37 CET - Sofia Kenin put in a superb performance to claim a comprehensive 6-0, 6-3 win over the in-form Belinda Bencic.
21:34 CET - No. 1 seed Jessica Pegula and 10th seed Yulia Putintseva have both progressed in Charleston, claiming straight set wins to seal spots in the last 16.
20:40 CET - Top seed Marie Bouzkova made light work of Raluca Georgiana Serban, soaring to a 6-1, 6-3 win to move into the quarter-finals of Bogota.
20:03 CET - No. 4 seed Emma Navarro was made to work by fellow American Hailey Baptiste, but had more than enough to beat her opponent, 6-4, 6-3.
Meanwhile, Ekaterina Alexandrova also moved through with a very straightforward 6-3, 6-0 victory over Ann Li.
19:52 CET - Former French Open champion Jelena Ostapenko overcame a tricky first set to defeat Louisa Chirico, 7-5, 6-2, and move through to the Charleston last 16.
19:01 CET - Alexandre Muller came from a set down to avoid an upset and secure his place in the next round at Marrakech. The Frenchman defeated Bolivian Hugo Dellien 6-7(5), 6-1, 6-4 to progress.
18:24 CET - Anna Kalinskaya is the next woman through in Charleston, battling from a break down on two occasions in the second set against Caty McNally to clinch a 6-1, 6-4 victory.
18:16 CET - Daria Kasatkina was in fine form to get her Charleston campaign up and running, brushing aside Lauren Davis, 6-1, 6-1, to move into the last 16.
Diana Shnaider also had little issue progressing, coasting past Polina Kudermetova, 6-3, 6-2.
16:40 CET - Play is set to get underway in Charleston in 20 minutes, with Daria Kasatkina playing her first match representing Australia, while Diana Shnaider and Anna Kalinskaya will also be taking to the court first up.
You can follow all the action from the WTA 500 event here.
16:35 CET - 36-year-old Roberto Bautista-Agut has been defeated in Bucharest, falling at the hands of Argentine Francisco Comesana, 6-4, 3-6, 6-3.
16:03 CET - Over in Marrakech, No. 7 seed Luciano Darderi and Vit Kopriva have both progressed to the last 16 with victories.
13:55 CET - Veteran Frenchman Richard Gasquet has been knocked out of Bucharet, losing to Flavio Cobolli in the last 16, 6-4, 4-6, 6-1. The triumph is a big moment for the latter, who has ended an eight-match losing streak. Meanwhile, Gasquet is set to retire from tennis at this year's French Open after a 22-year career.
11:33 CET - Eighth seed Camilo Ugo Carebelli has been knocked out in Bucharest, losing 6-3, 6-1 to world number 232 Filip Misolic.
11:15 CET - Good morning, and welcome back to the Tennis Tracker!
There is so much action to look forward to today, with veterans Richard Gasquet and Roberto Bautista Agut on court this morning in Bucharest.
But the best tennis takes place later this evening at around 17:00 CET, as the big seeds start their campaigns in Charleston and Houston.
Anna Kalinskaya, Diana Shnaider, Daria Kasatkina, Emma Navarro, Jessica Pegula and Tommy Paul are some of the names looking to begin the clay court season with a bang, and you can follow the results with us right here!