North Melbourne coach Brad Scott has launched a spectacular attack at the AFL's umpiring department, claiming that umpires told Kangaroos players they wouldn't pay free kicks for high contact to Lindsay Thomas "because he's a ducker."

As Scott bemoaned missed opportunities in his side's nine-point loss to Hawthorn on Friday night, the coach didn't hold back when questioned after the game if Thomas was unfairly treated.

Scott was asked about a period in the second quarter in which a free kick was paid against Thomas for a bump on Hawk Josh Gibson, and Thomas was denied an apparent free kick for high contact.

Questioned whether Thomas was dealt with harshly, Scott answered definitely.

"I know he is," Scott said.

"Because the umpires told our players that 'we know he's a ducker so we don't pay high free kicks to Lindsay'."

"They told our guys that.

"So that's clearly a pre-conceived idea. You just want the umpires to umpire what they see, not their pre-conceived ideas.

"It's for [umpires coach] Hayden Kennedy to deal with, not for me. Because they won't tell you what happened, that's for sure."

But Scott said the club would not be sending a "please explain" to the AFL. "Lindsay's just got to keep playing. The umpires have just got to do their job.

"Our instruction to Lindsay is just to keep playing.

"I thought that one was just an umpire reacting to an aggressive piece of play, and he got it wrong. We're not going to sit here and cry and moan about mistakes."

North had six more scoring shots and had 70 more disposals. Scott said that while North had done a lot right, they needed to be cleaner in front of goal.

"It was disappointing. We gave ourselves enough opportunity, Hawthorn took theirs. "You get what you deserve in this game."

The Roos look likely to be without Luke McDonald for at least a few weeks after he hurt his hamstring in the second quarter. Daniel Wells is also likely to be assessed after experiencing issues with his ankle and Achilles.

Hawthorn coach Alastair Clarkson said he was proud of his side after a match which he said had finals-like intensity.

"You don't usually experience that type of physical endeavour until later in the season," Clarkson said.