18:21 CET - Elena Rybakina is into the WTA Finals final! The Kazakh produced some brilliant rennis from a set down, eventually coming out on top 4-6, 6-4, 6-3 in a really high-quality affair with Jessica Pegula.
It is the first time she has ever reached the final at this event, and she will face the winner of Aryna Sabalenka vs Amanda Anisimova, which is up next!
17:40 CET - Cameron Norrie is into his first final of the season and his second-straight in Metz after battling back to clinch an impressive 4-6, 6-2, 6-4 victory over Lorenzo Sonego.
16:30 CET - Top seed Novak Djokovic is into the Athens final after claiming a comfortable 6-3, 6-4 win over Yannick Hanfmann. It is his 144th career final and interestingly, his 23rd in a different country.
He will also be eyeing his second title of the year and a 101st of his illustrious career.
15:55 CET - We are just minutes away from the first semi-final in Riyadh between Jessica Pegula and Elena Rybakina, and you can follow the clash live with Flashscore!
Pegula leads the head-to-head 3-2, but Rybakina won their last meeting convincingly at the Billie Jean King Cup Finals in September.
12:50 CET - Good afternoon and welcome back to the Tennis Tracker, on a fantastic day of semi-final action.
The main event undoubtedly comes from Riyadh, as the semis at the WTA Finals get underway. Up first at 16:00 CET is an encounter between the in-form Elena Rybakina and Jessica Pegula, before Aryna Sabalenka meets Amanda Anisimova in a mouthwatering rematch of their Wimbledon semi-final and US Open final.
Over in Athens from 16:00 CET, Novak Djokovic and Lorenzo Musetti will be in last-four action, while Cameron Norrie and Learner Tien headline proceedings from 15:30 CET in Metz.