Simona Halep saved a match point before defeating Canadian teen Bianca Andreescu 3-6, 7-6, 6-3 at the WTA Finals in Shenzhen.
Both players sought medical treatment during the match, with Halep getting her foot treated while Andreescu had a lower back problem.
Elsewhere, defending champion Elina Svitolina stretched her unbeaten run at the season-ending tournament with a 7-6, 6-4 win over Karolina Pliskova.
Halep and Svitolina are now 1-0 in the Purple Group, while Andreescu and Pliskova are 0-1.
Raphinha, Fermin score as Barcelona beat Athletic in home opener
Raphinha and Fermin Lopez scored as Barcelona beat Athletic Bilbao 2-0 at the Camp Nou on Thursday in their first home match of the LaLiga season.
Celtic and Rangers to play cup match behind closed doors after pitch invasion
'Old Firm' rivals Celtic and Rangers must play their next home Scottish Cup matches behind closed doors after clashes between the Glasgow clubs' fans following this year's quarter-final at Ibrox.
Chelsea and Fulham reach League Cup third round as Welbeck scores on debut
Chelsea has eased into the League Cup third round with a 2-0 victory over third-tier Luton Town on Thursday as Danny Welbeck marked his debut with a goal in Xabi Alonso's first competitive home match in charge.
PSG to meet Barca, Man City as Champions League draw throws up marquee ties
Champions League holders Paris St Germain will take on Barcelona and Manchester City in this season's league phase, while record 15-time champions Real Madrid will face Inter Milan and Arsenal after Thursday's draw in Monaco set up several mouth-watering clashes.
Abbas gives Pakistan slight edge as England battle back at Lord's
Pakistan bowler Mohammad Abbas took four wickets as his side just edged the first day of the second test against England at Lord's on Thursday although the hosts clambered back from a rocky start to end a weather-shortened day on 248-9.
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