Our number one could be seen thumping the floor in despair after Sylvain Legwinski netted Fulham's injury time winner in Wednesday's dramatic encounter at Loftus Road.
It was hardly the type of chance you'd expect a keeper to save - Legwinski was through one-on-one, centre of the goal and finished from about eight yards.
But Kasey reflected: "I was disappointed because I was able to make a couple of saves late but I wasn't able to come up with the last one."
Somewhat harsh on himself, perhaps? "No, that's what I strive for," Kasey countered. "That I can make the difference and when I come up short it sticks hard.
"To me, I don't give a damn that I make a couple of saves if we come away with no points.
"It was very disappointing. We know we let points slip. We want to to be battling away at the top end of the league all year, not just 'okay, we started off well, now let's just mess around'. That's not our intention at all."
Kasey's intention appears to be to make it impossible for boss Glenn Hoddle to drop him when Neil Sullivan, currently nursing a broken thumb, is back in contention.
He also appears driven by the fact that he was left on the bench by America in the World Cup - coach Bruce Arena opting for Brad Friedel instead.
"I had a disappointing summer and I wanted to put that right," Kasey insited. "I wanted to make sure I perform as well as I can.
"The guys have been tremendous in front of me and I'm just trying to build on that.
"We're all happy being top and that's what made Fulham more disappointing, a few results even went our way as well and we could have stamped our authority on the position. We have to make sure it doesn't happen again."
Kasey Keller was, according to stat kings Opta, the best goalkeeper in the Premiership in August - no surprise considering the standards he sets himself.