Simona Halep has edged out Victoria Azarenka this morning to move into the semi-finals of the US Open.

The Romanian won 6-3 4-6 6-4 in a rain-delayed clash in New York to reach the last four for the first time and set up a date with Flavia Pennetta in the process.

Azarenka, appearing in her fourth consecutive quarter-final at Flushing Meadows, made a perfect start to the match when she broke Halep in the very first game.

However, any questions over the number two seed's fitness following her injury scare in the last round were soon put to bed as she broke straight back to level things, going on to reel off four consecutive games to take control of the set.

The Romanian then held serve to love in her next two service games before going on to see out the set 6-3 at the first time of asking.

Azarenka refused to be beaten, however, and raced into a 3-0 lead at the start of the second set. Her progress looked to stall when Halep held and then broke to bring the score to 3-2, but some poor serving from the world number two allowed the Belarusian to break straight back.

Halep responded once more to bring it back to 5-4 when Azarenka was serving for the set, but the 20th seed ended a topsy-turvy second with her third break of the set to force a decider.

Fatigue may well have been creeping in for Halep, who was forced to three sets in the fourth round as well, and the opening game of the third set would have done nothing to help that as Azarenka came out on top in a titanic 10-minute tussle.

The two-time runner-up, ahead for the first time since the opening game of the match, broke again to move into a 2-0 lead, but Halep responded once more with an immediate break back before rain stopped play in New York.

Despite the lengthy delay, Halep maintained her momentum and pulled out another break in the seventh game to move 4-3 ahead.

The second seed kept her cool from there as she won two of the remaining three games to meet Pennetta in the semis.