Petra Kvitova of Czech Republic kisses the Ion Tiriac's trophy after winning the Madrid Open final tennis match over Victoria Azarenka of Belarus in Madrid, May 8, 2011. [Photo/Agencies]

* Biggest win of 21-year-old's career

MADRID - Petra Kvitova claimed the biggest win of her career and a third title of the season when she upset fourth seed Victoria Azarenka 7-6 6-4 in the final of the Madrid Open on Sunday.

The left-handed Czech 16th seed, who will break into the top 10 for the first time on Monday, overpowered Belarussian Azarenka with some booming groundstrokes to add to her successes in Brisbane and Paris.

The 21-year-old squandered a match point on the Azarenka serve at 5-3 in the second set but made no mistake a game later before raising both arms aloft in triumph.

"I played some of my best tennis today and this has been an amazing tournament for me," she said in a television interview beside the red clay court.

The rain that swept over the Spanish capital on Saturday had been replaced by bright sunshine for the final and the sliding roof of the Magic Box arena had been drawn back to reveal a bright blue sky dotted with whispy clouds.

The futuristic, 12,500-capacity stadium was only about a quarter full for the start of the match as the locals trickled in from lunch ahead of the eagerly-anticipated men's final between Rafa Nadal and Novak Djokovic later on Sunday.

Kvitova, like Azarenka a tall, aggressive player who likes to dominate opponents, made much the faster start on the sun-bathed court and opened a 3-0 lead after breaking her opponent's serve in the second game.

Azarenka claimed a break of her own to get the first set back on serve before Kvitova upped her game to take the tie-break 7-3 and a one-set lead.

She carried her momentum into the second set, breaking again in the opening game but both struggled to hold serve from then on until Kvitova confidently served out for her first win in one of the four premier mandatory events on the WTA Tour.