Eddie O'Sullivan has warned his Ireland team they must meet Scotland head-on if they are to maintain their superiority over their Celtic rivals.
The Irish have won every RBS 6 Nations match against Scotland since 2001 and they are favourites to extend that run at Croke Park this afternoon.
But O'Sullivan fears the damage a beefed-up Scots side can do and has outlined to his Triple Crown holders where the contest will be won and lost.
He said: "Physically, Scotland have been very hard for us to handle over the last couple of years and we've lost a lot of collisions. Today the starting point is we have to win the collisions.
"There's nothing new in that - it's the same for every game - but recently against Scotland it's an area we've struggled in.
"Last year at Murrayfield in the Six Nations it was a hugely physical game and they disrupted us by being in our faces. It took us a long time to wear them down.
"It was more of the same for the World Cup warm-up match in August when we also didn't cope very well with the physicality they are now using to great effect.
"It will be physical again today and we have to make sure that at the very least we break even in that department of the game."
Scotland's limitations have been exposed by France and Wales in this year's Six Nations so coach Frank Hadden is attempting a new approach.
At fly-half Hadden has swapped the assured kicking game of Dan Parks for the greater running threat posed by Chris Paterson and O'Sullivan expects the change to have a telling effect.
"Chris is a very different player to Dan Parks. He's a ball-in-hand player, can go to the line and distribute," he said.
"He's elusive and that's why he's also been able to play on the wing and at full-back for Scotland.
"His selection at fly-half changes the dynamics of the team and is a statement of intent on Scotland's part.
"It seems they are moving away from the very physical forward-dominated game with a big back five in the pack.
"We don't want to over-read anything so we'll keep an open mind, but we expect them to come at us from different angles.
"Paterson will be the trigger for that."
