Sam Stosur in action during her first-round loss to Caroline Wozniacki at the US Open; Getty Images

Wozniacki beats Sam in US Open first round

NEW YORK, AAP –¬†World No.2 Caroline Wozniacki has ended Sam Stosur’s US Open campaign before it really started.

Undone by eight double-faults and 34 unforced errors, Stosur fell to a 6-3 6-2 first-round loss to the reigning Australian Open champion in oppressive heat at Flushing Meadows.

Champion in 2011, Stosur missed last year’s event with a wrist injury and lasted just 84 minutes on Tuesday.

Up against the game’s steadiest player, Stosur had stressed the importance of striking a balance between controlled aggression and loose tennis.

But she was unable to deliver on Arthur Ashe Stadium, the sport’s biggest stage, where she brought down the great Serena Williams in the final seven years ago.

“I thought I played a pretty decent match. I’m actually proud of myself with what I was able to do out there,” Stosur said.

“Obviously there were things I wasn’t so happy with but, overall, I was obviously playing a quality opponent and gave it everything I had.

“The one thing that probably did let me down was my second serve. I was trying to go for it but my rhythm was a bit off, maybe my ball toss was a bit off, and that equated to those double faults.

“But she’s No.2 in the world at the moment for a reason.”

Stosur made a confident enough start, firing down two aces to open the match.

But after an easy first service hold, the veteran dropped three straight games to fall behind 3-1.

The world No.67 fought hard to retrieve the break and level the set up at 3-3, only to cough up three double-faults in a horror service game to all but hand Wozniacki the first set.

Stosur did well to hold serve after an epic 18-point fourth game of the second set but was broken for 4-2 and then, somewhat appropriately, dropped serve to love with her eighth double-fault on match point.