Sania Mirza dug deep into her reserves to overcome a fighting Anne Keothavong 6-4 7-5 to progress to the singles quarter-finals of the USD 220,000 Pattaya Open, here today.

The unseeded Indian, ranked 111, tamed the giant-killing British rival in a hard-fought second round match after one hour and 40 minutes struggle. Keothavong, ranked 88, had shocked second seed and world number 16 Dominika Cibulkova of Slovakia in the opening round.