World number 83 Flavia Pennetta has admitted that she did not expect to reach the semi-finals of the US Open prior to the tournament.

The Italian overcame compatriot Roberta Vinci on Wednesday with a 6-4 6-1 victory, and is still yet to drop a set at Flushing Meadows.

Having secured progress to her first-ever Grand Slam last-four bout, Pennetta is delighted with her recent displays.

"From the first day of the tournament I never thought I would be here and be talking about the semi-finals," Pennetta told reporters, "I didn't play my best tennis in the last six months, and I just tried to keep working and working the same way every day.

"I'm starting to feel more my forehand, my backhand. Everything is starting to feel more normal in the way it was before the injury.

"I'm playing really good tennis here. Every day is much better. Every day was tougher and I've adjusted, tried to use everything I have and take it to the court and play my best tennis."

Pennetta will now face Victoria Azarenka for a place in the final.