00:13 CET - That's that for today's tennis, but join us again in the morning for our continued coverage of the WTA Finals and the tournaments in Athens and Metz!
00:08 CET - There was a dramatic end to the action in Metz, with Frenchman Arthur Cazaux losing 6-7, 7-6, 6-2 to seventh seed Cameron Norrie in an epic battle that lasted for two hours and 46 minutes, with the first two sets alone lasting 135 minutes.
23:35 CET - The final match of the day in Athens was won by sixth Nuno Borges, who overcame a one-set deficit to beat Eliot Spizzirri 5-7, 6-3, 6-4.
Next up for Borges is Djokovic.
21:07 CET - Lorenzo Sonego has upset fourth seed, and fellow Italian, Flavio Cobolli 2-6, 6-3, 7-5 in Metz to book the first quarter-final berth in the French city. With a weak field, Sonego might be eyeing a title at the season-ending event.
20:14 CET - Novak Djokovic has beaten Alejandro Tabilo, who had won their last two meetings, 7-6, 6-1, to book his spot in the quarter-finals in Athens.
The top-seeded Serb battled through the first set on his return to the courts after some injury troubles, but made light work of the second set.
Next up, he will face the winner of sixth seed Nuno Borges and Eliot Spizzirri, who play in the day's last match in the Greek capital.
19:08 CET - Aryna Sabalenka wins a thriller! The world number one has fought back from a break down in the final set to beat Jessica Pegula 6-4, 2-6, 6-3.
She now needs to win just one set in her final match against Coco Gauff to advance.
18:51 CET - Eighth seed and home favourite Corentin Moutet has been knocked out in Metz, losing 3-6, 7-6, 7-6 to Aleksandar Vukic after failing to convert two match points in the final set.
Over in Athens, Sebastian Korda and Marcos Giron have both progressed, and Novak Djokovic is now playing to join them in the quarter-finals.
18:29 CET - We're into a deciding set in Riyadh, as Jessica Pegula has fought back brilliantly against Aryna Sabalenka to level the contest at 4-6, 6-2.
Follow the conclusion of the match here.
17:52 CET - Aryna Sabalenka is closing in on the semi-finals in Riyadh, with the world number one battling through a competitive opening set against Jessica Pegula to take it 6-4.
Follow the second set right here.
16:59 CET - Next up in Riyadh is a clash between two familiar foes, with world number one Aryna Sabalenka taking on Jessica Pegula for the fourth time this season.
Sabalenka won two of the previous three, but Pegula won their most recent meeting as well as their last clash at this tournament, in 2023.
The American will seal her place in the semi-finals if she wins.
16:48 CET - Coco Gauff is up and running at the WTA Finals, with the reigning champion romping to a 6-3, 6-2 win over Jasmine Paolini, seeing off the Italian in one hour and 20 minutes to get her first win of the tournament.
That's now two losses in two for Paolini, who has to beat Jessica Pegula in her final match and hope other results go her way.
16:19 CET - After just under three hours, Tomas Martin Etcheverry has claimed a 6-7, 7-6, 6-3 win over American qualifier Mackenzie McDonald in Athens.
15:59 CET - Defending champion Coco Gauff is a set to the good in her must-win clash against Jasmine Paolini at the WTA Finals. The American took it 6-3 in 40 minutes.
Elsewhere, Daniel Altmaier is through in Metz after a solid 6-4, 6-4 win over sixth seed Arthur Rinderknech, while qualifier Yannick Hanfmann has advanced in Athens.
14:42 CET - The first match of the day in Metz was an all-French affair, and it's been won by lucky loser Kyrian Jacquet, who has beaten Luca van Assche 4-6, 6-3, 6-4.
This was the first ATP win of Jacquet's career.
10:36 CET - Today's headline action comes at the WTA Finals in Riyadh, where defending champion Coco Gauff faces Jasmine Paolini at 15:00 CET, with both players needing a win after defeats in their opening matches.
Following that clash, the other game in the Stefanie Graf Group sees world number one Aryna Sabalenka take on Jessica Pegula, as both women target a spot in the semi-finals.
Elsewhere, there's plenty of action at ATP events in Metz and Athens, with Novak Djokovic, Flavio Cobolli and Cameron Norrie among the standout names involved.
Check out the full schedules in Metz and Athens via the links.
10:00 CET - Good morning and welcome to our coverage of today's tennis in Riyadh, Metz and Athens!