New York, NY, USA, 1 September 2015 | tennis.com.au/AAP

Update 5.50am: West Australians Casey Dellacqua and Matt Ebden have been bundled out of the US Open in straight sets in the first round on Monday.

Dellacqua fell to Estonian qualifier Anett Kontaveit 7-5 6-2 before Ebden succumbed 6-4 6-2 6-4 to 17th seed Grigor Dimitrov.

Dellacqua, who reached the fourth round last year, fell behind a break midway through the first set and never recovered.

Despite nudging ahead 2-1 on serve in the second set, the 30-year-old then dropped five straight games to lose in 64 minutes.

The Aussie faces a rankings dip after being unable to defend her significant haul of points accrued in 2014, but was philosophical in defeat.

“I didn’t take any of last year’s results into today’s match. It’s a new year. Every tournament you play is a new tournament,” she said.

“I came up against a girl that was full of confidence coming through qualifying, playing well and unfortunately I didn’t bring my best stuff.

“You never take qualifiers lightly because they’re really tough, and she’s young. She’s 20, she’s got nothing to lose, she was going to throw the kitchen sink at me and she did – and she did it well. Credit to her.”

It was a tough draw for Ebden, up against the former top 10 talent on Court 5.

Despite the fact that Dimitrov is currently down from his career high mark of world No.8 set this time last year, the Bulgarian nonetheless exhibited impressive form, blazing 21 winners to just 14 errors to advance.

“The main thing (was) I didn’t serve well, he served really good. Probably that was the biggest difference today – he served a lot better than I did. Everything flows from there,” Ebden said.

“You always want to do better, but in a way I’m on a good path for this year. I’ve had lots of matches; I think I’ve won more matches this year than any other year up until now.”

Ebden had earlier reached the main draw after three wins in the qualifying draw.

Fellow Australians John Millman, Sam Groth and Daria Gavrilova will be in action later on Monday.