Tackle height change could leave players 'sitting ducks': Ireland's Farrell

“If you are ever just saying to a kid 'you need to tackle lower', then you become even more vulnerable in my opinion,” said Farrell.

“If you're just sitting there with your arms in front, trying to wrap, with your head down, you're a sitting duck.

“The coaching and technique of how it's applied to tackling below the waist is absolutely crucial, otherwise we're going to have a serious problem.”

Ireland flyhalf Jonny Sexton, speaking at the Six Nations launch on Monday, said the rule change may actually increase the number of concussions in the sport.

“Of course we need to get the head shots out of the game, but the tackles we really need to take out of the game are the reckless, out of control, sprinting out of the line,” he said.

“It's not like you can't get concussed by chopping someone's knees. I see a hell of a lot of concussions from people getting their head on the wrong side, a knee to the temple or a hip even to the side of the head. So, I strongly disagree.”