LONDON, June 16 (Xinhua) -- Former world No. 1 Rafael Nadal made an early exit at the ATP Queen's Club grass-court tournament with a three-set defeat by unseeded Ukrainian Alexandr Dolgopolov here on Tuesday.

The Spanish fifth seed, who won the Stuttgart Open last week, went down to the 79th-ranked Dolgopolov 6-3, 6-7 (6-8), 6-4 after one hour and 42 minutes.

French Open champion Stan Wawrinka of Switzerland defeated Australia's Nick Kyrgios 6-3, 6-4 in just 49 minutes, and defending champion Grigor Dimitrov of Bulgaria completed a 4-6, 6-3, 6-4 victory over American Sam Querrey.

Top seed Andy Murray of Britain beat Yen-Hsun Lu of Chinese Taipei while US Open champion and fourth seed Marin Cilic defeated Frenchman Adrian Mannarino 7-6 (7/3), 3-6, 6-2.

Nadal, who has slipped to 10th in the world rankings after his quarterfinal defeat at the French Open, said that he had tried his best.

"I was fighting in every point," Nadal said. "I was with the right concentration, with the right motivation, not giving up when I had tough moments.

"I'm not happy I lost a match that I had a chance to win, but that's it. That's tennis on grass."