Italy’s Flavia Pennetta desperately wants to make it through to the semi-finals of the US Open for the first time but the prospect has left her with a heavy heart.

If she is to achieve her goal, Pennetta will have to do so at the expense of one of her closest friends, Roberta Vinci, with the pair drawn to play each other after winning their fourth round matches on Monday.

“I think it’s going to be just a really tough match for both of us,” Pennetta said after beating Romania’s Simona Halep 6-2 7-6.

“We know each other really well... 20 years or more, because we live almost in the same place.”

Pennetta had to regain her composure after a long rain delay to reach the quarters with a straight-sets win over Halep that was anything but routine.

After winning the opening set and building a 4-2 lead in the second, Pennetta suddenly lost her way as the hard-hitting Halep reeled off the next three games in a row.

Then she reached set point on her own serve before play was suspended.

The match did not resume for nearly five hours but when it did, Pennetta burst out of the blocks to stun her opponent.

Pennetta has never made it past the fourth round at any of the other grand slam but has flourished on the Flushing Meadows hardcourts, reaching the quarter-finals in the Big Apple in 2008, 2009, 2011 and now this year.