London, Nov 5 - Seventh seed Stanislas Wawrinka of Switzerland stunned fifth-seeded Tomas Berdych in the opening game of the ATP World Tour Finals here Monday.

Wawrinka, qualifying for the season-ending tournament for the first time, won 6-3, 6-7 (7-0), 6-3 in two hours and 25 minutes, reported Xinhua.

The Swiss rose to fame in this year's US Open where he defeated Andy Murray in the quarterfinals.

"It was a dream come true to win on my debut here," the world number eight said after the match.

"I have watched many times on TV and today I was here on court. I'm happy to get the win. It's never easy on your first time here but I'm happy with way I played today."

Wawrinka was drawn in Group A with world No. 1 Rafael Nadal, David Ferrer and Berdych. (IANS)