The WTA Finals in Singapore 2015 singles and doubles events begin tomorrow with first day of six days of Round Robin matches before the semi finals on day 7 (Saturday 31 October) then finals day (on Sunday 1 November).
The WTA Finals 2015 schedule of play is determined well before the tournament begins and list exactly which matches will be played each day for example 1 doubles match then 2 singles matches followed by 1 doubles match.
The Order of Play or “OOP” is released in the afternoon prior to the day the next round of matches will be played. Not so long ago the first order of play for the WTA Finals 2015 draw was released with both singles Round Robin matches being played by the Red group and one match each from the Red and White groups for the doubles.
The Order of Play is the sequential order that the matches are scheduled to be played for each day and which players exactly will be competing. In the order of play list, all players will have a number in brackets next to their names which represents what seed they or their team is i.e.  for the No.1 seed.
The 2015 WTA Finals in Singapore order of play for Day 1 of this 8-day tournament is:
Sunday 25 October
At 11am: White – Bethanie Mattek Sands/Lucie Safarova  v  Carla Suárez Navarro/Garbiñe Muguruza
followed by: Red – Kristina Mladenovic/Timea Babos  v  Andrea Hlavackova/Lucie Hradecka