10:20 CET - There is some unfortunate news coming out of Tokyo. Jack Draper (22) has had to retire from his clash with Ugo Humbert (26) trailing 5-7, 1-2, after he seemingly picked up an abdominal injury. Humbert moves through to the semi-finals as a result, and will face Tomas Machac (23).
09:48 CET - Despite dropping a thrilling first set, US Open finalist Jessica Pegula (30) found a way through Veronika Kudermetova (27), clinching a 6-7(9), 6-1, 6-2. It is 17 wins in her last 19 matches for Pegula, with her only losses coming in finals to Aryna Sabalenka.
09:36 CET - Karen Khachanov (27) was involved in a real tussle with Francisco Cerundolo (26), eventually coming out on top in China 7-6(4), 7-6(9).
Meanwhile, over on the women's side, Elina Avanesyan (22) was shocked by Ukraine's Yulia Starodubtseva (24), falling to a 3-6, 1-6 loss.
08:20 CET - Tomas Machac (23) has followed up his win over Tommy Paul in Tokyo, beating Alex Michelsen (20) 7-6(2), 6-3 to move into the semi-final.
07:35 CET - Good morning, and welcome back to the Tennis Tracker this Sunday!
We have had some early results from Beijing, with Lorenzo Musetti (22) being stunned 2-6, 4-6 by Yunchaokete Bu (22), who claimed a massive victory on home soil.
Diana Shnaider (22) also fell to Magdalena Frech (26) 6-0, 3-6, 3-6, but Paula Badosa (26) secured safe passage with a 7-5, 7-5 win over Rebecca Sramkova (27).
Currently on court is Jessica Pegula (30), who is facing off with Veronika Kudermetova (27), while Karen Khachanov (28), Tomas Machac (23) and Elina Avanesyan (22) are in action.
Andrey Rublev (26) and Jack Draper (22) are set to play their matches very soon, while Carlos Alcaraz (21), Naomi Osaka (26) and Coco Gauff (20) all take centre stage a little later today.