FLAVIA PENNETTA continued Italy’s outstanding US Open last night as she outlasted a drained Petra Kvitova to reach the semi-finals at Flushing Meadows.

On a hot, humid day when temperatures again passed 90 degrees, the 33-year-old Pennetta had more in the tank than two-time Wimbledon champion Kvitova as she clinched a 4-6, 6-4, 6-2 victory to join Roberta Vinci in the semi-finals.

Czech Kvitova, who is still getting over mononucleosis which was finally diagnosed earlier in the summer, led by a set and 3-1 but by the end she looked like she was running on empty and Pennetta took full advantage to reach the last four for the second time, against the winner of last night’s match between Victoria Azarenka and Simona Halep.

Pennetta said conditions had made things very difficult for both women. "I think it's everything, not just the heat [but] the tension for the match, what you think you have to be, what you want to be and to do,” the Italian said.

“So many things on your mind, you try to take out everything and just play tennis. The second set I was really in trouble, but I was just keep going.”

As her energy levels drained away, Kvitova’s game fell apart and the errors flew from her racket.

“Just from the beginning of the match I didn't really feel 100 percent ready today,” she said. “I'm just glad that I left everything I could today [on the court]. I suffered a lot, but I'm still here. That's good.

“I was kind of hot out there today. But energy-wise wasn't probably the best today, as well.”

The possibility of an all-British doubles final took a step closer to becoming reality after Dom Inglot joined Jamie Murray in the semi-finals.

Inglot joined forces with Swede Robert Lindstedt to beat sixth seeds India’s Rohan Bopanna and Florin Mergea of Romania 7-6, 6-3.

Inglot and Lindstedt will play Pierre Hugues-Herbert and Nicolas Mahut of France today while Murray and Australia’s John Peers face Americans Steve Johnson and Sam Querrey for a place in a second straight grand slam final.

As well as the carrot of a US Open final, today’s matches could also have an effect on the Davis Cup next weekend.

Both Murray and Inglot will be in the Britain line-up for the semi-final against Australia in Glasgow, so a final between the two might add a little extra spice.