Maria Sharapova’s chance of usurping Serena Williams as the women’s top ranked player by year end was dealt a major blow following a three-set loss to Caroline Wozniacki in their opening White Group match of the WTA Finals.

Wozniacki had beaten the Russian second seed in their last meeting at the US Open and managed to repeat the feat in Singapore today in a gruelling encounter that lasted a little over three hours.

A close first set was decided when Wozniacki claimed the final five points in the tie-break while Sharapova edged the second set, also via tie-breaks, to send the match into a deciding third set.

At this point, Wozniacki took full advantage of a streak of unforced errors by Sharapova to get a break of serve early in the set, going on to break her Russian opponent’s serve twice more to claim a 7-6, 6-7, 6-2 win.

Speaking afterwards, Sharapova stated ”It’s happened the last couple of times I played against her. The chances that you have when serving for a set, it’s in your hands to finish that off. When you give those chances back, you’re not just going to run away with the match”

Wozniacki meanwhile attributed her win to her training regime ahead of her participation in the New York marathon, stating ”I kept thinking to myself out there in the third set, `If you’re going to get tired now, how are you going to get through this marathon? You better keep going”

As a result, Sharapova now needs to at least reach the final and hope Serena loses her two remaining round-robin matches in order to overtake the American and finish the season with the top ranking for the first time.