Second-seeded Nadia Petrova of Russia grabbed the trophy of the Tournament of Champions in Sofia after unexpectedly beating top seed Caroline Wozniacki on Sunday.

Petrova gave Wozniacki surprisingly hard time throughout the final match of Qatar Airways Tournament of Champions in Bulgaria's capital.

Thanks to her high speed, stability and solid, seamless performance the Russian clinched her victory 6:2, 6:1 against the Danish star, who very often appeared toothless in her game and failed to impede her opponent.

Caroline Wozniacki however produced one of the best shots in the tournament – a short shot that took advantage of Petrova's inability to move quickly inside the court.

Local commentators lauded Petrova's coach Ricardo Sanchez for studying carefully the Danish star's style and knowing well her vulnerable points.

A day earlier Petrova defeated Roberta Vinci of Italy 6-7 (8-10), 6-1, 6-4 in a dramatic match that lasted 2 hours, 42 minutes.

Caroline Wozniacki, who began this year as Number one in the WTA rankings, was the group leader due to her high ranking in WTA.

Making it to the final and playing for her third title (after Seoul and Moscow) ensured Wozniacki's return to the top 10 when the rankings are updated on Monday. She will rise from No. 11 to No. 10, swapping with Marion Bartoli.

For Petrova, this is the third title of the year. During her previous four matches with Wozniacki, she had suffered defeats.

The tournament in Sofia featured eight tennis players, two of whom received a "wild card" - the best Bulgarian female tennis star Tsvetana Pironkova and Russian Maria Kirilenko, who is No. 15 in the rankings.

The 2012 WTA Tournament of Champions is a singles-only tennis tournament that was played on indoor hard courts in Sofia's Arena Armeec hall.

This was the fourth edition of the tournament, part of the 2012 WTA Tour.

The 2012 edition was the first to be held in Sofia, having been relocated from Bali, where the tournament was held for the previous three years and called the Commonwealth Bank Tournament of Champions.

Sofia will host WTA Tournament of Champions next year too.