Hawthorn coach Alastair Clarkson will caution his players against breaching the protected area after watching Richmond concede five free kicks under that rule on Thursday night.

Before the start of the home and away season, the AFL foreshadowed umpires would strictly enforce the protected area of eight-to-10 metres around the mark. 

That proved to be the case in the season opener between the Tigers and Carlton, with the reigning premier repeatedly penalised after its players entered the protected area, several of those free kicks resulting in easy goals to the Blues. 

Clarkson told reporters on Friday the umpires' strict enforcement of the protected area on Thursday hadn't been unexpected, but said he would again address the rule with his players before their Round 1 clash with Collingwood on Saturday night. 

"It always is [enforced strictly] early in the year and then it seems to taper off a little bit, so the really interesting part is just whether that's maintained over the course of the season," Clarkson said.  

"We're obviously mindful of that and need to educate our players a little bit, just making sure that they're wary of an infringement being incurred because it's a significant penalty. 

"As we saw last night, Richmond infringed on about six occasions and I think three or four of them ended up being easy goals from the top of the goalsquare.

"That has a pretty significant impact on the scoreboard, so we have to be mindful of that."

Read: 10 players to watch in Round 1