Iga Swiatek began her bid to regain the world number one ranking with a comeback success over Barbora Krejcikova at the WTA Finals.
Poland’s Swiatek trailed the Wimbledon champion by a set and double break before regrouping to win 4-6 7-5 6-2.
This was the 23-year-old’s first match since her quarter-final US Open exit in September and first under new coach Wim Fissette.
“At the beginning I felt a bit rusty but I’m happy that I found a way to play a bit more solid,” said Swiatek.
She and Aryna Sabalenka are in contention to finish the year as the top-ranked player.
Defending champion Swiatek will need to win the title to replace Sabalenka, while the Belarusian needs to win all three round-robin matches or reach the final.
Coco Gauff takes on fellow American Jessica Pegula in the second Orange Group match later on Sunday.
The top two players from each group advance to the semi-finals. Sabalenka, Elena Rybakina, Jasmine Paolini and Zheng Qinwen are in the Purple Group and play on Monday.
The tournament is being held in Saudi Arabia for the first time – a move which has been criticised by some because of the country’s human rights record.
French Open champion Swiatek took an extended break after the US Open, pulling out of tournaments in China for personal reasons before splitting with her coach of three years.
She arrived in Riyadh early to get the feel of the courts but her performance was scrappy in the opening stages of the match.
Broken in the first game, she had opportunities on the Krejcikova serve but her forehand in particular let her down.
Krejcikova, who finished outside the top eight in the world rankings but was given a place on account of being a Grand Slam champion, served out the set and quickly went a break up in the second.
Swiatek double faulted in her next service game to hand her Czech opponent a double break and gestured angrily at her box, before regaining her composure.
She cut down on the unforced errors to bring the set level at 3-3 and then benefited as Krejcikova threw in a horrible service game to concede the set.
Swiatek kept the momentum going into the decider and led an increasingly hampered Krejcikova 5-0 before sealing victory after two hours and 35 minutes.
