The AFL's new rules governing substitutes and concussion are already causing conundrums for coaches just one match into the 2011 season.

Carlton were forced to make their substitution earlier than expected in Thursday night's game against Richmond when key-position player Jarrad Waite was forced from the ground late in the second term after a clash of heads.

Under the new guidelines, once the club doctor deemed Waite was concussed, he was unable to return to the field, prompting Carlton coach Brett Ratten to replace him with substitute Kane Lucas.

The Tigers made their switch midway through the third term, when midfielder Nathan Foley - who was battling a bout of gastro - was replaced by Daniel Connors.

"When you make the change you can't take it back," said Ratten.

"... maybe with a bit more time Jarrad might have been able to come back on, but that's the rules, you deal with it."

Collingwood coach Mick Malthouse predicted clubs would be very reluctant to use their substitute before halftime unless their hand was forced, as was the case with Waite.

"All best-laid plans tend to get a little bit skewiff by the sheer nature of the game," Malthouse said on Friday.

"You go in with certain strategies in regard to that substitution player and for one reason or another it changes.

"No-one would have thought Waite would be first off for Carlton, he wouldn't have and the coach has indicated he didn't think that would be the case.

"That would have thrown their plans out."

AFL football operations manager Adrian Anderson insisted that Carlton had been treated more fairly under the substitution rule than would have been the case in previous years.

"One of the three key reasons for the rule is to try and assist a team when it has an injury early in the game, that it's not disadvantaged in terms of the number of players it can rotate on the bench," he said.

"This is a really good example of a situation where a doctor has made a right call in the interests of the welfare of the player.

"We don't want to see concussed players out on the ground risking further damage."

Another aim of the substitutes rule is to free up some of the congestion caused by the ever-increasing number of tactical interchanges.

That appeared to happen in the second half of Carlton's 20-point win over the Tigers, although Malthouse said it was too early to judge.

"Round one is notorious for mistakes, tiredness, players that you think have done a wonderful pre-season and played all the practice matches and all that sort of stuff," said the 2010 premiership coach.

"The intensity of round one is dramatic compared to the last game you've played.

"Whether it be a NAB final or NAB Challenge in the bush, whatever it is, it hits you like a ton of bricks.

"It's longer, the stakes are far greater.

"You see some great round one matches, but five or 10 minutes into the last quarter the blokes are running around on sheer guts alone."

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