Jackie McNamara admitted his Dundee United side had been beaten by the better side after watching Kilmarnock triumph at Rugby Park.
The Scottish Premiership leaders lost 2-0 to the Ayrshire side and McNamara expressed frustration at his team's display.
"There were too many that weren't at it tonight," he explained.
"We were beaten by a bit more desire and willingness to chase lost causes and work hard for the team."
The Tangerines boss refused to use Kilmarnock's artificial surface as an excuse for United's performance.
"It doesn't matter what pitch you're on," he said.
"They should be confident, they should be wanting to go and express themselves properly. They [Kilmarnock] managed to get their full-backs forward at times, we didn't.
"I know they're better than that and so far this season they've been up to everything that's been put to them.
"Credit to Kilmarnock, they were confident here and you can see why they've done well at home. We got beaten by the better team tonight."
United front-man Nadir Ciftci tried to go straight up the tunnel after being replaced with Ola Adeyemo in the second half but was ordered back to the dugout area by McNamara.
"I told him to sit down," said the manager of Ciftci.
"It was a frustrating night for him. I don't think he was the only one that didn't perform for us."
United may yet go into the international break as Premiership pacesetters with second-place Hamilton Academical facing Celtic on Sunday and Inverness - a point behind Accies and three off United - taking on Ross County, also on Sunday.
"The disappointing thing is that we've got to wait two weeks to get this out our system for the Partick Thistle game, but we need to do better than we did tonight," added McNamara.