Danny Simpson knows Leicester need to quickly get to grip with the new grappling laws after set-piece sloppiness cost the reigning champions at Manchester United.
The Foxes are still basking in the afterglow of last season's incredible title triumph, with the 5,000-1 shot flourishing as the big guns faltered thanks to camaraderie, attacking flair and defensive solidity.
The latter has proved harder this season and Saturday's 4-1 loss at Manchester United took their goals conceded tally to 11, with their third Premier League loss already as many as the Foxes fell to in the entirety of the 2015-16 campaign.
Set pieces were to blame on Saturday as United scored from three Daley Blind corners, with Claudio Ranieri's men appearing to struggle to adapt to law changes that now sees referees get tough on shirt-pulling and blocking in the box at set pieces -- something full-back Simpson admits they need to get their head around.
"Err, I have to be careful what I say,'' the full-back said. "It is in your mind, yes, we have seen a few decisions this season. It is in your mind.
"It is something we have to learn to adapt to as players. They have changed the rules.
"The way it was last season, I thought we were very good at defending set pieces and we made it tough for the opponents and you have been doing that for all your career and suddenly you have got to change it
"But it's the same for everyone, it's something we have got to work on and look at.''
Simpson says the defensive collapse seen at United "can't happen again'' and hopes Leicester can bounce back as well as they did after losing 4-1 at Liverpool earlier in the month.
City responded by winning their first ever Champions League match 3-0 at Club Brugge and have the chance to do something similar when Porto arrive on Tuesday for their first home match in the competition.
"That is the spirit of our team, we know we are good at bouncing back,'' Simpson said.
"In general play we were okay today, we were ourselves, even when United had the ball. It was just those set pieces.
"We have to go again, we have a massive game on Tuesday again, our first in the Champions League at home and we will have to turn it around.''