SINGAPORE - Agnieszka Radwanska secured her first win of the BNP Paribas WTA Finals Singapore presented by SC Global in her final round robin match on Thursday with a convincing victory over last year's finalist Simona Halep and in the process eliminated the top seed from this year's competition.

The Pole needed a tiebreaker to claim the first set before breaking Halep three times in the second set to record a 7-6 (5), 6-1 victory in the Singapore Indoor Stadium.

Radwanska was 1-5 down in the tiebreak but recovered to win the next six points and the opening set which lasted 74 minutes.

Said world No. 2 Halep: "If I had won it, maybe mentally I would have been stronger and could have won the match."

But from there, the 26-year-old world No. 6 was in irresistible form and broke her opponent three times to take the next set in just 29 minutes.

Said a disappointed Halep: "I am tired and I go home for a good holiday. I think I had a good year."

With Maria Sharapova beating US Open champion Flavia Pennetta 7-5, 6-1 in the later match, Radwanska has qualified for the semi-finals of the US$7 million (S$9.75 million) season-finale.

This is the second straight year that Radwanska has advanced to the semis after losing two group matches.

There was more to celebrate as her victory over Halep was also her 500th WTA career win.

Said Radwanska: "I think I was really playing great tennis today. That was I think much better tennis than the other days. I didn't really play bad, it's just today everything seems like it was working for me. Was really good quality tennis the whole match."