Queens Park Rangers were beaten 3-1 by Fulham yesterday.
QPR were beaten 3-1 by Fulham on Saturday afternoon and they rarely showed any threat against their London rivals.
Rangers were well short of their best at Loftus Road, and Hasselbaink could only say sorry to his side’s fans after the defeat.
"I must say sorry to the fans," the Dutch boss said. "We let them down and we let ourselves down and it wasn't good enough. Now we have to look to try and put this right.
“Fulham deserved their win. We never got started. We’ve had quick starts in the past, but that didn’t happen today.
“What we’ve done well in previous games, we did really, really averagely today. And Fulham capitalised on that.
“It’s a bitter pill to swallow. This result is hard to take.”
QPR had become more resilient in recent weeks under Hasselbaink’s stewardship, but they were worryingly poor against the Cottagers.
The R’s never got to grips with Fulham’s 3-5-2 formation, with Ross McCormack, Moussa Dembele and Tom Cairney all getting on the score-sheet for the visitors.
Hasselbaink has now won just two of his first 12 matches in charge of the London club, and sizeable improvements need to be made sooner rather than later.
QPR have had a disappointing campaign so far, and yesterday’s defeat to Fulham has surely ended any slim chance they had of making the play-offs.