Reigning US Open champion Samantha Stosur recorded a confident straight sets win over Maria Sharapova to win her first Round Robin match at the TEB BNP Paribas WTA Championships, a season ending Grand Finale, being played here in Istanbul, Turkey.

Click here to relive Stosur's best moments in the match.

Stosur made a superb start to the match and broke Sharapova's serve in the second, and then, fifth game to win the first set 6-1.

The second set opened with a shift in momentum when Sharapova got a crucial break to reel off three games in a row, just to lose the next three to the feisty Russian. As the match progressed, both players challenged each other in long rallies before Sharapova faltered in the eleventh game and gave Stosur a chance to complete the straight sets win with a 6-1, 7-5 scoreline in 93 minutes of play.

Earlier today, World No.1 Caroline Wozniacki registered a come-from-behind win over Polish star Agnieszka Radwanska and joined Czech Petra Kvitova as the other winner of Day One at the Championships.