New Haven, CT, USA, 18 August 2014 | AP/AAP

Casey Dellacqua’s US Open preparations have been cut short after she was knocked out in the first round of the Connecticut Open.

Just a week out from the US Open, American Alison Riske beat the Australian 6-1 6-4 on Sunday.

Dellacqua broke Riske’s serve in the first game, but the 43rd-ranked Riske won the next six games to clinch the first set.

At 4-4 in the second set, Riske broke the 30th-ranked Dellacqua’s serve then closed out the match.

In other results, Flavia Pennetta of Italy beat Klara Koukalova of the Czech Republic 6-1 6-3; the sixth-seeded Pennetta used two straight aces to clinch the win.

Camila Giorgi of Italy won 6-3 6-1 over American Coco Vandeweghe. Giorgi fell behind 3-1 in the first set, but rallied to win the next five games.

Giorgi had four aces and only one double-fault in needing just 24 minutes to win the second set.

Ekaterina Makarova of Russia beat Roberta Vinci of Italy 6-3 6-3.

The 18th-ranked Makarova has reached the semifinals of her last two tournaments in Washington and Montreal.