Hyderabad, Aug 12 - India's Saina Nehwal defeated Anastasia Prokopenko of Russia 21-10, 21-17 to advance to the pre-quarterfinals of the World Badminton Championships here Wednesday.

It took World No 6. Saina a mere 27 minutes to dispatch the feeble Russian challenger. She will next face 10th seed Petya Nedelcheva of Bulgaria who beat Aiying Xing of Singapore 26-24, 19-21, 21-16 in a tough encounter.

Saina, who was down with chicken-pox a week back, showed no signs of tiredness even though she committed a couple of unforced errors in the second game.

Prokopenko was no match for the Indian who engaged her Russian opponent in long rallies before going for the kill.

Saina, India's best medal hope in the tournament, said she had done her homework for the match.

'I was playing her for the first time. She also plays doubles and yesterday I came to see her match. I was ready with a plan.'

'She is a very good net player and is good with the dribble. She has a good smash. So, I decided to go more for rallies than quick-finishing smashes.'

'I was not feeling tired so that's a good sign.