Adelaide United coach Aurelio Vidmar admits his team was not up to scratch after the 0-0 draw with Queensland Roar last night.

Vidmar said the heavy recent schedule for the Reds may have made it tougher than he expected.

"We were certainly not up to scratch but I can't fault the players' endeavour," Vidmar said in his post match assessment.

"We gave the ball away a lot, especially in the first half but that's the way it is. We tried to push as much as we could in the second half but it was just one of those nights.

"Playing four games in ten days and then Sunday's game will be five in 15 (days), that's a pretty tough ask in anyone's book, so it was a bit of a cagey performance from both sides.

"They gave everything they possibly could, sure they were fatigued but at least the endeavour was there and I think if we can freshen up a bit that will obviously help heading into Sunday."