Joe Schmidt’s holders entered the championship as favourites to retain their crown, but, after suffering an opening weekend defeat to England, they now travel to Edinburgh with those aspirations hanging by a thread.
Scotland, on the other hand, kicked off their tournament with an at-times impressive five-try bonus-point win over Italy.
Horne knows that with trips to Paris and Twickenham - two venues where the Scots have never triumphed in the Six Nations era - still to come, Gregor Townsend’s side cannot afford a slip-up at home if they are to make a bid for the title.
However, the Glasgow centre reckons it will be the visitors who will be under most strain at Murrayfield and says Scotland are determined to exploit the wounds left by their first Dublin defeat since November 2016.
“Ireland will be feeling a bit of the pressure,” said Horne. “We put ourselves under pressure too, but I guess it will be in the back of their minds that if we beat them their title dreams are gone.
“At the same time we will feel pretty similar, so we’ll look to fly into them and have a good game. I heard Rory Best saying the game against us will be a real measure of their character.
“They will be looking for a massive reaction, which makes them dangerous. They will be looking to prove last weekend’s defeat was just a bump in the road.
“But there will be some [doubt] in the back of their minds if we can start well. We’ll be looking to make it a difficult day and put them under some early pressure.”
However, Horne expects a team that had won 18 out of 19 matches before losing to Eddie Jones’ men to come out fighting.
He said: “We need to be wary. Ireland are a world-class side. They’re ranked second in the world for a reason.
“Up until the weekend they were probably the world’s form team, but England were outstanding.
“Gregor said to us today it is going to be one of the biggest challenges any of us has ever faced and that’s the way we’re treating it.
“They’re a fantastic side who have got threats all over the pitch - but on the flip side, we’re ready for it. This is why we play rugby.”
Horne sat out the Azzurri clash with a knee injury, but admits he may have to settle for a seat on the bench this weekend after watching Warriors colleague Sam Johnson impress on his Test debut.
“I’m good friends with Sam and I thought it was a great first cap,” he said. “I was really chuffed for him. He moved the ball well, communicated with Finn Russell and defended well too.
“It says a lot about the depth we’ve have in the centres when we have a lot of guys out injured that a debutant comes in and plays like that.
“We have so many guys putting their hands up for selection. Chris Deans has had a great season and is champing at the bit, Squiggs (Nick Grigg) is desperate for a shot too.
“You’ve got guys like Alex Dunbar, Matt Scott and Duncan Taylor still to come back, so you can’t afford to take your eye off the ball.
“You have to take your chance when you get it, whether that’s 20 minutes off the bench or being 24th man helping the team get ready. When you do get a starting jersey, you have to put everything into it.”