Hyderabad, Aug 13 - India's Saina Nehwal fought her way through to the quarterfinals of the World Badminton Championships, beating Bulgarian Petya Nedelcheva in three game in the pre-quarters of the women's singles here Thursday.

Saina rallied from a game down to beat Nedelcheva 18-21, 21-18, 21-10 with the home crowd providing her throaty support at the Balayogi Indoor Stadium, Gachibowli.

India's top mixed doubles pair Jwala Gutta and Valiyaveetil Diju made it a hearty evening for the hosts by entering the quarterfinal, defeating 12th seeded Robert Mateusiak and Nadiezda Kostiuczyk of Poland 21-11, 22-20.

The eighth seeded Indian duo will next face defending champions and second seeded Indonesian pair of Nova Widianto and Liliyana Natsir. Gutta and Diju, however, have beaten them earlier when they were No.1 pair.

In men's singles' Chetan Anand bowed out after losing to sixth seeded Sony Dwi Kuncoro of Indonesia 16-21, 16-21.

For Saina it was her best performance at the World Championships and will be up against second seeded Chinese Lin Wang in the next round. The 19-year-old Indian had defeated her in the final of Indonesian Open to win the nation's maiden Super Series title this year.

'It was a tough game today. But I am happy with the fitness level. I was not feeling tired and by the third game I was at my best. I think tomorrow will be a tougher match,' said Saina, who has just recovered from chicken pox.

Saina was in trouble when she lost the first game which went neck and neck. The Indian picked up pace and broke free from 13-13 and pocketed four points. She was leading at 17-13, but then lost the grip on the game. Petya raised her level and picked eight points.

The Indian was completely in command in the second game and led 12-6 and then 18-10. Her deceptive drop shots had the Bulgarian in trouble. Petya, however, pocketed eight points in a row to draw parity, but Saina managed to put it across.

In the third game, the Bulgarian was visibly upset after two close line calls went against her as Saina took a crucial 6-2 lead. That proved the turning point of the game. Saina then maintained her calm and retrieved whatever came her way in the longest rally of the match in the next point.