Tenth seed Tim Henman crashed out in the first round of the Rogers Cup after being beaten in three sets by Slovakia's Dominik Hrbaty on Monday.
Henman has not won a match since Wimbledon
Henman was also beaten in his first match at the Legg Mason Classic last week and has not won since Wimbledon.
The British number one won the first set but lost momentum after winning Hrbaty's first service game in the second and lost 3-6 7-5 6-1.
Henman admitted that his form ahead of this month's US Open was "frustrating".
"It certainly hasn't shown in my results yet, but I'm a big believer the hard work you put in will pay off somewhere down the line," said Henman.
"It is frustrating. I haven't played that much tennis and that many matches.
"I'd love to be winning and getting on a roll, but I'm not putting any extra pressure on myself."