Singapore: Sania Mirza and her Swiss partner Martina Hingis lifted their ninth title together this year, beating the Spanish pair of Garbine Muguruza and Carla Suarez Navarro to clinch the WTA Finals women's doubles trophy here on Sunday.

Sania and Martina, the top seeds, prevailed 6-0, 6-3 over their eight-seeded rivals in a lopsided summit clash, which lasted little over an hour.

Before this, Sania and Martina had won eight titles (Indian Wells, Miami, Charleston, Wimbledon, US Open, Guangzhou, Wuhan and Beijing) and finished runner-up just once (Rome - falling to WTA Rising Stars Timea Babos and Kristina Mladenovic).

The Indo-Swiss pairing dropped serve only once through the match and broke their opponents five times to wrap up a comprehensive victory.

Sania and Martina are now unbeaten in 22 matches, stretching back six tournaments. In fact, since their last defeat -- to Chan Hao-Ching and Chan Yung-Jan in Cincinnati -- they have dropped just two sets.

Muguruza and Suarez Navarro -- late replacements in the draw after Casey Dellacqua and Yaroslava Shvedova's withdrawal -- were completely outplayed in the match.

In the second game, Sania unleashed a ferocious forehand to break Muguruza.

The second set was more competitive, but Sania and Martina did not let go of their supremacy and wrapped up after little over an hour on court.

"It's incredible. I feel like it was a perfect day. The energy was a bit better in practice and Sania just played out of her mind. She was everywhere today - on her side, behind me - it's about choosing the right partner," said Martina.

This triumph is especially huge for Martina as the trophy was her 50th WTA doubles title, a milestone only 15 players have reached.

Sania and Martina ended the year as the world No. 1 doubles team and Sania said a win in the WTA Finals is the perfect way to wrap up the year.

"To play in tournaments like this is what we've fought all our lives for and it's incredible to play in front of a packed stadium," said Sania.

"We feel very fortunate. We've done some amazing things together and it's the perfect way to end the year for us... We're on cloud nine," she added.

In singles, an emotional Agnieszka Radwanska claimed her maiden WTA Finals title with a roller-coaster 6-2, 4-6, 6-3 victory over Czech Petra Kvitova.

Playing a first final in her seventh appearance at the season-ending event, the sixth-ranked Pole also created history by becoming the first woman to lift the title after completing round robin play with a 1-2 record.

"A few weeks ago I didn't even know I would be here," a tearful Radwanska said in a courtside interview.

"I was doing the right thing in the important moments of a really close match. I had my chances in the second set but it doesn't really matter how I won," the Pole added.

In stark contrast to her semi-final victory over Maria Sharapova, Kvitova made a lacklustre start to the match with a sloppy opening service game, handing her opponent an immediate break as she got off to the worst possible start.

The Czech appeared a little more animated in the second game and despite working a few openings, poor shot selection and a string of unforced errors enabled the world number six to survive the threat and move 2-0 ahead.

The double Wimbledon champion finally got on the scoreboard in the third game thanks to a pair of aces but unable to make any inroads on the Radwanska serve, the Czech recorded her third double-fault in as many games to cough up yet another break.

Exuding confidence, Radwanska breezed through her next service game and was able to wrap up a dominant set in 33 minutes with another routine hold.

Radwanska carried that momentum into the first game of the second set, running down everything and breaking the Czech with an unreturnable backhand volley at the net and consolidating her advantage with a solid hold to win her third game in a row.

Kvitova, who continues to battle mononucleosis, stopped the rot to claim her first game of the second set, screeching in delight at a forehand winner as she attempted to stir herself into action.

Her efforts bore fruit three games later when the powerful left-hander forged her first break point of the contest and levelled at 3-3 with a booming crosscourt forehand winner.

An easy hold put her ahead for the first time in the set and suddenly the crowd had a contest to watch after Radwanska's march to victory was halted and Kvitova completed the comeback with a second consecutive break to set up a decider.

THE HOT PAIR

Sania Mirza and her Swiss partner Martina Hingis’s win in Singapore on Sunday was their ninth title together this year, including 2 Grand Slams.

The following is the list of their titles in 2015:

March 20: Indian Wells Masters
April 4: Miami Open
April 12: Family Circle Cup
July 11: Wimbledon
September 13: US Open
September 26: Guangzhou International Open
October 3: Wuhan Open
October 10: China Open
November 1: WTA Finals