Ross County boss Derek Adams feels signing a new defender is a priority after they slumped to their fifth defeat in six games.
Goals from Chris Johnston and Kris Boyd sealed at Victoria Park, with Stuart Kettlewell's strike not enough for the home side.
The result means the Ayrshire men leapfrog County, leaving them second bottom and only propped up by Hearts.
And Adams admitted: "We haven't started the season well enough this year."
It is a far cry from County's fifth-place finish last season, and Adams warned fans to prepare for a long hard season.
He said: "We know we've overachieved over the years. We know we're in the Premiership and we know where we got last season, but this season was always going to be survival for a club of this size.
"We just keep on working away and trying to find a positive result.
"It's a difficult league we're in but we're only six points off seventh place.
"You only have to look at St Mirren a few weeks ago. They were down at the bottom end and look where they are now."
County found themselves trailing after just seven minutes, but a well worked move had them level 12 minutes before half-time.
Rocco Quinn started a fine four-man move that also involved Graham Carey and, after Melvin de Leeuw's shot was blocked, Kettlewell netted the rebound from the edge of the box.
However, Boyd restored Killie's lead before the break, and could have increased their advantage in the second half.
"We started the game very well and we took the game to Kilmarnock," added Adams.
"We passed it well and had good possession, and they've scored against the run of play.
"It's disappointing but defensively we didn't do enough today."