Serra Zanetti, a 25-year-old Italian from Modena, was ranked in the world's top 100 when she was only 18, but after serious shoulder surgery plummeted to 252, only to rebuild her ranking to 83 last year.

Hingis took advantage of her eighth break point to go 3-1 up in the first set and broke again to take it in 38 minutes.

The 'Swiss Miss' broke for a third time to lead 2-0 in the second but Serra Zanetti showed admirable fighting spirit to hit back immediately.

However, Hingis was not to be denied and made it three breaks in a row before sealing the contest on her fourth match point.

This was the first time Serra Zanetti had met Hingis since their junior days and afterwards Hingis admitted she was not surprised by the quality of her opponent's play.

"She was pretty tough, yeah, but I would expect that after she got into the quarter-finals."

"I think it was important for me today to get a speedy player. She was very fast and sometimes she went down the line when you didn't expect them. She played very well."