Yes, next up it's the utterly brilliant Serena Williams, chasing the Serena Slam, having already won the three previous Majors this year.

Her record in Grand Slams this year? Won 26, lost 0. Her record at the US Open over the last four years? Won 26, lost 0. Her record against Roberta Vinci? Won 4, lost 0.

Good luck with that one, Roberta.

Image source, Reuters

So, a good day for Italy so far. It could even be an all-Italian final, with Roberta Vinci playing the next semi-final. There is quite a formidable obstacle in her way though...

Image source, Getty/EPA

Image source, Getty Images

Here's Flavia Pennetta, speaking to the on-court interviewer: 

"It means everything," she says. "I think I played really well - I didn't know how to handle the pressure. It's amazing to be on a court with a crowd like this, who always support me."

Piers Newbery
BBC Sport at Flushing Meadows

"'Mamma Mia, Flavia!!!' An actual quote bellowed from the press seats in front of me. Pennetta looks much the sharper and fresher, and well on course to complete the first half of an all-Italian final. That would go down well here, I'm sure."

Everything is working for Pennetta at the moment - she's causing Halep real problems on her backhand in particular. Halep is melting away here - she surrenders the game to love and has now lost the last 15 points in a row...

Image source, Getty Images

Pennetta is tracking everything down like a venerable police sniffer dog - she latches onto a Halep forehand and belts it back past her. The Romanian, who has slipped back into bad habits again, fires long, and is suddenly facing three break points. Pennetta needs only one - nailing a forehand down the line. She's two holds of serve away from the final...

Pennetta isn't the type of player who is going to pummel every ball, but she is very adept at building through a point and picking her moment to unleash the power. Some hefty winners take her to 40-0, and she seals the deal with a lovely backhand-forehand one-two punch. Level pegging.

Image source, Getty Images

Pennetta's not going to lie down though - she absolutely hammers a forehand into the corner to bring the New York crowd to their feet. Both women are hitting the ball with real venom and precision now, and the winners are flowing. An over-the-shoulder putaway volley, a shot honed on the doubles court, gets Pennetta to 15-30, and then she forces Halep to go long - two break points for the Italian. A double-fault follows, and Pennetta is back on track in what is turning into a real topsy-turvy scrap of a second set.

For the first time in this match, it's Pennetta with a few questions to answer - how can she respond? Suddenly, Halep is more pumped up than an over-inflated lilo, and she takes the first point with a searching backhand into the corner. Pennetta responds well, taking the next two points, but a lucky net cord for Halep drags her back to 30-30. 

Halep drills a forehand down the line to get to deuce, and just like that, Pennetta sends two groundstrokes long. Halep in charge in this second set.

Image source, Reuters

We haven't seen much of Halep's trademark feistiness so far, but there's a glimpse as she nails a forehand and celebrates with a wild double first-pump. Suddenly the Romanian has a bit of momentum behind her, and she finds the corner with another forehand. She nails a backhand down the line, and for the first time, she has a lead on the scoreboard.

Image source, Getty Images

Halep can only hope that the occasion gets to Pennetta - who has never been in a Grand Slam final - and it just looks like it might. A wayward forehand coughs up 0-30, and just when it looks like Pennetta has got herself back on track, she misses the easiest of volleys and all of a sudden, Halep has three break points. Pennetta fires long, and Halep, without really doing anything, is back in this match.

Halep headed off court during the changeover there - she needs to find a way to reverse the momentum here. But it's not getting any better - Pennetta is battering her with deep groundstrokes, and she sets up an easy putaway that opens up 0-30. 

Halep is struggling to control her power - another backhand flies long and Pennetta has two break points. Halep nets, and her aspirations of making the final are heading south faster than a flock of gulls in the winter.

Image source, Reuters

Piers Newbery
BBC Sport at Flushing Meadows

"The media seats are not surprisingly dominated by Italians, always one of the larger press packs on the tennis tour, and they are living every moment of this. One wayward Pennetta volley prompted a magnificent cartoon slap of the forehead from a compatriot, while fists were clenched and knees squeezed as she took the set. A collective discussion is under way in the changeover, disbelief and smiles all round."

Legendary Romanian gymnast Nadia Comaneci is in the stands to support her compatriot Simona Halep. Perfect 10? I'll give her a 3 so far, and that's being generous. The second seed is wobbling like a novice on the balance beam, and she surrenders the first set in double-quick time when Pennetta nails a backhand down the line. What a first set from the Italian...

Image source, EPA

Halep is showing all the patience of a kid at Christmas here - she's trying to unwrap the big forehand at every opportunity, and more often than not it's ending up in the net. A couple of poor misses give Pennetta two more break points.

On the first point, the Italian does everything right, opening up the court, but then nets a rather too casual over-the-shoulder volley. Pennetta fires wide to pass up the second opportunity too. She's not letting Halep out of jail though - shot of the day, absolutely belting a forehand into the corner, flatter than a pair of slacks that have just been through the trouser press. Break point number three - and this time Pennetta takes it by forcing a forehand error. The Italian will serve for the first set...

Pennetta is moving really well, chasing everything down at the back of the court and hitting crisply off both wings, She's growing in confidence, and Halep's frustration is mounting - a few wild groundstrokes help Pennetta to a straightforward hold.

Image source, Getty Images

Halep is giving the forehand plenty of welly today, but she shows a silky touch too, dinking a delicate drop volley off her toes to fox Pennetta. More shenanigans at net, and this time Pennetta comes out on top, reacting well to punch a volley past the Romanian. 

Halep puts a little too much mustard on another forehand, and suddenly out of nowhere, it's two break points for Pennetta. She manoeuvres Halep around the court superbly, but then sends a creaky backhand into the tape with the court gaping. On the next point though, it's Halep's turn to net, and Pennetta, who has more breaks of serve in this tournament than anyone else, has another one.

Piers Newbery
BBC Sport at Flushing Meadows

Image source, Getty Images

"It's dry, bright, 21C and with a cool breeze in Arthur Ashe Stadium - unusually kind conditions for tennis after the recent extremes of lung-scorching heat and biblical storms. There are probably 4,000 spectators in place, which is not bad for a Friday morning but it does leave 20,000 blue plastic seats on show. It's a marathon not a sprint today though."   

Pennetta is playing in only her second Grand Slam semi-final, and she shows the first sign of a few jangly nerves with a double fault. That allows Halep to claw her way to deuce. A tight backhand from the Italian finds the tape, but she manages to save the break point when Halep sends a gimme backhand wide. 

A long forehand from Halep and a big serve from Pennetta, and just like that the door is slammed on the Romanian.

Image source, Getty Images