Sania Mirza's opening singles match of the 2006 season ended in disappointment as she was outclassed by Venus Williams in the quarter-finals of the Watson Water Champions Challenge in Hong Kong on Thursday.

The world No. 34 Indian lost 3-6, 3-6.

The 19-year-old powerful groundstrokes once again impressed as she accounted for 15 winners against the nine by the American, ranked 10th in the world.

But the total tally of 37 unforced efforts made the difference as her opponent had only 28.

This was the second meeting between the two players. Venus had won the previous encounter 6-3, 6-2 at Stanford last year.

The winners of the quarter-finals progress to the semi-finals in the Gold Group, while the losers play each other in the Silver Group semi-finals.

Sania will now face Czech Republic's Nicole Vaidisova, who was beaten 6-2, 6-2 by Lindsay Davenport.

Sania and Kim Clijsters had beaten Serena Williams and Venus 8-7 (7/2) in a best-of-15 games single set match in the doubles event on Wednesday.