Dimitrov upsets Thiem in 1st round of ATP Finals

London, Nov 14: Grigor Dimitrov defeated Austria's Dominic Thiem 6-3, 5-7, 7-5 here in the opening match of the Pete Sampras Group at the ATP Finals.

World Number 6 Dimitrov, the first Bulgarian to qualify for the season-ending championship in the 48 years since its founding, battled for two hours and 21 minutes to beat fourth-seed Thiem on Monday, Efe news reported.

The 26-year-old Bulgarian broke his Austrian rival three times to win the match.

Thiem, ranked fourth in the world, won the Rio Open and was a finalist in Barcelona and Madrid. 

He also reached the semifinals at Rome and the French Open.