Romanian second seed Simona Halep advanced to her first US Open semi-final Wednesday by defeating two-time Australian Open champion Victoria Azarenka of Belarus 6-3, 4-6, 6-4.

Halep advanced to a Thursday semi-final against Italy's 26th-ranked Flavia Pennetta, who upset Czech fifth seed Petra Kvitova, a two-time Wimbledon winner, by 4-6, 6-4, 6-2 in another quarter-final at Arthur Ashe Stadium.

Pennetta has a 3-1 career edge in matches against Halep.