Martina Hingis is back in the doubles semi-finals of a Grand Slam for the first time since the 2002 Australian Open as she and Flavia Pennetta reached the US Open last four in their first major as a team.

Hingis, one of the greatest women’s players of all time with five Grand slam singles titles, 43 WTA Tour singles crowns and various spells atop the world rankings between 1997 and 2001, took up competitive doubles again in 2013 after six years in retirement.

An early partnership with Daniela Hantuchova failed to gel.

And even though she nabbed the Miami doubles with German Sabine Lisicki in March, Hingis said things didn’t really click until she teamed up with Pennetta, a partner she can count on in key moments of a match.

“You have to have the right partner who helps in these moments,” Hingis said.

“The most important thing is you have to trust and rely on your partner.

“That’s what I feel with Flavia – she’s there when I’m down, she’s there when some things don’t always work, we’re always there for each other.”

The two didn’t know each other well, but Hingis said that facing Pennetta across the net in doubles had convinced her the Italian was the partner for her.

“I was really impressed with Flavia last year when we played against each other in Cincinnati,” Hingis said.

“It felt almost like we were playing singles against each other. It had to happen sooner or later is how I felt.”

Pennetta, who is also through to a singles quarter-final clash with world No.1 Serena Williams, felt the same.

In Hingis she’s found the doubles partner she’d been seeking since she stopped playing with Gisela Dulko, with whom she won a dozen titles including the 2011 Australian Open women’s doubles crown.

“When I stopped playing with Gisela it was very difficult for me,” Pennetta said.

“I changed (partners) a lot trying to find the good feeling, the good one – and I think I found her.”

The duo beat fifth-seeded Kveta Peschke and Katarina Srebotnik on Tuesday to reach the semis, fighting back from 1-3 in the first set en route to a 6-4 6-3 win.

For a place in the final they’ll face third-seeded Cara Black of Zimbabwe and Sania Mirza of India.