Second-seeded Iga Swiatek has rallied to beat Barbora Krejcíková 4-6, 7-5, 6-2 in her first match in two months at the WTA Finals in Saudi Arabia.
Meanwhile, Coco Gauff enjoyed a successful start by beating fellow American Jessica Pegula 6-3, 6-2.
Swiatek, who arrived at the WTA Finals with new coach Wim Fissette, had not played a match since losing to Pegula in straight sets in the US Open quarterfinals in September.
Before taking on the job with second-ranked Swiatek, Belgian Fissette had coached major champions including Kim Clijsters, Naomi Osaka, Angelique Kerber and Simona Halep.
"Even though I played a lot of those [practice] matches, I kind of forgot for a while how it is to feel all those things, a bit different stress and emotions," Swiatek said after ending a highly successful three-year partnership with coach Tomasz Wiktorowski.
"For sure, I needed some time to adapt. The most important thing was that even though it happened, I managed to fight through that. And was patient enough to wait to get better."
Swiatek rallied from 3-0 down in the second set to turn it around against Krejcíková, who has been hit by injuries and had played only 29 matches coming into the finals. Seven of them were victories at Wimbledon.
In the all-American showdown, Gauff converted five of her eight break-point opportunities against Pegula to win her opening match at the year-ending tournament for the top-eight players.
"I thought we both were playing high level," Gauff said.
"I just think I was able to break through on the more important points."
Gauff will face Swiatek on Tuesday with the winner taking control of the Orange Group. Pegula will next face Wimbledon champion Krejcíková.
On Saturday, top-ranked Aryna Sabalenka eased to a straight-sets victory over Zheng Qinwen in the opening match of the finals in Saudi Arabia.
Fourth-seeded Jasmine Paolini of Italy beat fifth-seeded Elena Rybakina in the other Purple Group match.
Swiatek is the defending champion.
AP
