Heather Watson was knocked out in the second round of the Rogers Cup after a 6-4 6-3 defeat by Andrea Petkovic.
The British number one, 23, made light work of Irina Falconi in the opening round but her faltering serve was capitalised upon by German Petkovic.
Defeat means Watson misses out on a match with Serena Williams, who she came so close to beating at Wimbledon.
The Briton lost in three sets to the world number one last month, with Williams going on to win the title.
Everything you can clean in one app Speed up and optimize your Mac now!