Upset of the previous day:
Flavia Pennetta def. Roberta Vinci 6-4 6-1
Flavia finally does it! She reaches her first US Open semi-finals at the age of 31! This is also her debut semi-final appearance at a Grand Slam after being on tour for such a long time. She defeated the current top 2 Italian players to reach this stage and will no doubt rocket up the rankings next week. Roberta is denied of her top 10 ranking once again, but she did defend her points from last year.
Serena Williams vs. Li Na
Serena will be the hot favourite to reach the finals yet again, as she leads the heads to heads 8-1. Li has already achieved her personal best result here, so she has nothing to lose. Against Serena, Li will need to hope Serena misses her first serve. Because it is almost impossible to get an aggressive return off Serena's massive first delivery. These 2 players always have tough matches, so I'm expecting a close set at least. Still, Serena's mental toughness and home crowd will prove too much for the Chinese.
Pick: Serena in 2 sets
Flavia Pennetta vs. Victoria Azarenka
Another player who has nothing to lose, Pennetta will go out swinging against the favoured Belarussian. Their heads to heads is tied at 1-1, with Pennetta winning their only hardcourt meeting in 2011. Does that account for anything? Well, Azarenka has improved leaps and bounds since then, and Pennetta's ability to sustain high level of play is suspect. Victoria seemed a bit shaky in her recent matches, so Flavia needs to irritate her by bring a lot of balls back and attacking the net. If she can continuously do it, Azarenka might unravel. However, I believe Azarenka will still win this as she's mentally tougher than Flavia.
Pick: Azarenka in 2 sets