The WTA Finals in Singapore had the White Group in action for the third and last rotation. Ostapenko scored a flawless win over Pliskova, but in the end, the result didn't matter in the final picture. The second tie drew in all the heat as Garbine Muguruza challenged Venus Williams in a winner-takes-all encounter. Pliskova had won the group after the second session, thus the real battle was for the second available slot.

Williams, who made her first appearance since the WTA Finals moved to Singapore, was eager to end the season in style. That level of commitment followed her during the match, as she fought hard to get herself back on track when trailing from behind.

Her opponent from Spain was trying to match the result from two years ago, when she reached the semis.

Venus Williams avenged the Wimbledon loss

Although nothing can compare with a Grand Slam win, Venus Williams didn't forget how Muguruza bludgeoned her in the Wimbledon final earlier this year. With that in mind, she dug up all the resources she had in her possession to conquer the challenge.

The opening set had both players attacking. A quick exchange of breaks in the middle of the set enhanced the drama. At 5-4, Muguruza served to stay in the set. The very next game saw a sharp Venus getting her nose in front one more time. The world No. 2 had to serve again to prolong the fight, but Venus pressed harder to finally convert the third set point opportunity she had.

The second act had Muguruza taking an early lead. With a 3-1 deficit to recover and 0-30 on her own serve, Williams backed herself up from the brink of collapse to recover and keep the set. Some furious exchanges from the baseline increased the thrill from Singapore indoor venue. All the efforts Muguruza put in were for nothing, as somehow her opponent kept standing firmly on the ground.

Eventually, she went on to convert the second match point, on Muguruza's serve.

Venus digs deeper, Muguruza ends her world No. 1 bid

Ranked fifth in the world, Venus Williams can finish the year a few places higher. On the other side, Garbine Muguruza's hopes and dreams for a world No. 1 seat when the dust will settle are gone.

The best case scenario at the end of the week would have her in the current slot. For that to happen, Pliskova must lose in the semis, while Wozniacki and Svitolina must not win the event.

The White Group delivers two players for the next round,Pliskova and Williams, while Muguruza and Ostapenko are done for this season.