Tennis Tracker: Gauff knocked out by Kalinskaya in Dubai, Rublev stunned by Mensik in Doha

23:30 CET - The quarter-finals are underway in Los Cabos with world number 12 Casper Ruud (25) taking on Portugal's Nuno Borges (27) for a place in the semi-finals.

That is where we leave you tonight, come back tomorrow for semi-final action from Doha and Dubai as well as quarter-final matches in Rio and Los Cabos.

23:25 CET - After the high of a stunning victory in his home tournament in Buenos Aires last week, Facundo Diaz Acosta (23) has been brought back down to earth with an early exit in Rio, losing 6-7 (1-7), 6-3 to fellow Argentine Sebastian Baez (23).

21:40 CET - The day’s action is underway in Rio de Janeiro and Cameron Norrie (28), Dusan Lajovic (33) and Thiago Seyboth Wild (23) have all won to book their spots in the quarter-finals.

Keep up with the action in Brazil here.

20:28 CET - The first major upset of the day in Dubai comes from the quarter-final match between Coco Gauff (19) and Anna Kalinskaya (25).

World number three Gauff won the first set 6-2 but was outplayed in the second and third sets by Kalinskaya who won 2-6, 6-4, 6-4. Kalinskaya will face world number one and heavy favourite Iga Swiatek (22) in tomorrow's semi-final.

19:21 CET - A huge win for Gael Monfils (37)! The French veteran has beaten compatriot and world number 18 Ugo Humbert (25) 6-2, 6-4 to move into the semi-finals in Doha. 

17:47 CET - Jakub Mensik's (18) fairytale run continues! After knocking out fifth seed Alejandro Davidovich-Fokina (24) and 2023 finalist Andy Murray (36), the teenager has now beaten top seed Andrey Rublev (26) 6-4, 7-6 to move into the semis in Doha. 

17:40 CET - World number one Iga Swiatek (22) has extended her winning streak to seven matches with a 6-3, 6-2 victory over Australian Open runner-up Qinwen Zheng (21).

15:08 CET - Second seed Karen Khachanov (27) has moved into the semi-finals in Doha, with opponent Emil Ruusuvuori (24) being forced to retire after just three games. 

14:11 CET - Alexei Popyrin (24) has defeated Alexander Bublik (26) in the first quarter-final in Qatar. The match finished 6-4, 6-4.

13:23 CET - It has just been announced that Elena Ryabkina (24) has withdrawn from the Dubai Championships after falling ill. As a result, Jasmine Paolini (28) will automatically go through to the last four. 

11:16 CET - Holger Rune (20) has reunited with former coach Patrick Mouratoglou after the world number seven's partnership with Boris Becker and Severin Luthi ended following a disappointing Australian Open campaign last month.

Read more here.

10:12 CET - Today's action begins in just under an hour with Marketa Vondrousova (24) playing the first quarter-final of the Dubai Championships against Sorana Cirstea (33).

08:40 CET - To begin with, we bring you news of an overnight upset in Mexico, where third seed Alex De Minaur (25) was knocked out of the Los Cabos Open by Alex Michelsen (19), losing 6-4, 6-1.

There were no such issues for the three other players competing in the tournament, with Alexander Zverev (26), Casper Ruud (25) and Stefanos Tsitsipas (25) all advancing without too many problems. 

To catch up on everything that happened yesterday and in the early hours of this morning on the ATP Tour, click here.

08:20 CET - Hello and welcome to Flashscore's live coverage of today's tennis!