Former world number one Simona Halep is bidding for her first WTA Tour Finals triumph, having finished runner-up in 2014
Wimbledon champion Simona Halep survived match point before beating Canadian teenager Bianca Andreescu in a pulsating WTA Finals clash in Shenzhen.
The 28-year-old Romanian was on the brink at 6-5 in the second set before taking her third set point in the tie-break to force a decider.
US Open champion Andreescu required lengthy treatment on her back before Halep clinched a 3-6 7-6 (8-6) 6-3 win.
Earlier on Monday, defending champion Elina Svitolina beat Karolina Pliskova.
The Ukrainian world number eight edged an 18-minute first set tie-break before sealing a 7-6 (14-12) 6-4 win.
Both players broke each other early in the opening set before the marathon tie-break which Svitolina clinched when the Czech's backhand landed wide.
Svitolina's break in the seventh game of the second set proved decisive as she claimed a seventh successive victory at the WTA Finals.
