Flavia Pennetta stunned Simona Halep to reach her maiden grand slam singles final with a straight-sets victory in the last four of the US Open at Flushing Meadows. 

Second seed Halep was strongly fancied to win Friday's first semi-final - which had been put back a day due to inclement weather 24 hours earlier.

However, the Romanian delivered an error-strewn display at Arthur Ashe Stadium and was emphatically punished as Pennetta - a semi-finalist in this event two years ago - surged to victory in 59 minutes.

The world number 26 could yet face fellow Italian Roberta Vinci on Saturday, although a clash with world number one Serena Williams, who is seeking a calendar grand slam, appears much more likely.

Having survived a break point in her second service game, Pennetta immediately enjoyed success on the Halep serve before holding with comfort to open up a healthy lead in the opener.

The 33-year-old was guilty of missing a backhand volley that would have put her two breaks up, but it mattered little as some powerful hitting led to Pennetta moving 5-1 ahead at the third attempt.

Halep saved one set point, only to be left powerless as a thunderous backhand down the line saw the underdog move ahead.

After making 14 unforced errors in the first set, Halep continued to look well short of her best as Pennetta broke at the start of the second set. 

The second seed broke back to love as errors crept into Pennetta's game and, with her forehand suddenly firing, Halep swiftly opened up a 3-1 lead when her opponent went long.

Yet Pennetta was soon back in charge as she got back on serve in the next game before breaking again at the next opportunity to leave a place in the final tantalisingly close.

A love hold made it 15 points in a row for the Italian and there was to be no way back for Halep as she slumped to defeat amid a flurry of winners from Pennetta.