When you look at past World Cups, Ireland's tendency to take teams for granted has at times proved fatal.

Then there was 2015. Same story. We won all four pool games and looked like we were heading towards something big, but suffered even more knockout heartache against Argentina.

Yes, Saturday's match against Scotland may still be in the pool stages, but this is effectively knockout rugby. It's a massive game and Ireland can't afford to be caught on the hop.

Given their form, it would be easy for this Ireland team to let their minds drift towards who they could face in the quarter-finals and take their eye off the ball a bit.

Were that to happen, there is no better team than Scotland to swoop in, take advantage of a lack of focus and deliver a killer blow to the great Irish dream.

Ultimately, while the South Africa game had a lot of glamour and hype attached to it, Ireland were always going to need to win this one. Now that it's come down to it, Ireland must put their impressive record against Scotland to the back of their minds and get the job done on the night.

It must have bothered Scotland to see Ireland reach 14 points after three games while they sat on zero points having played once against South Africa. With the way the fixtures and rest weeks fell, Ireland were able to build early momentum while Gregor Townsend's side were left to reflect on a loss to the Springboks before they could get points on the board.

But Scotland deserve credit. They've done everything they could do to keep themselves in the hunt and set up a do-or-die showdown with Ireland.

For Ireland, with expectations and excitement around the team at an all-time high, a pool-stage exit would be a disaster.

Thankfully, this group of players have time and time again demonstrated their ability to hone in on the task at hand and block out all the noise. Sixteen times, to be exact, if we limit that to their current winning run.

And there's no better example of Ireland keeping their cool in the face of adversity than the Six Nations game against Scotland at Murrayfield earlier this year.Injuries really stretched Ireland and wreaked havoc on their gameplan, to the point at which Josh van der Flier was throwing the ball in at the line-outs, but they adapted and still won by two clear scores to set up a Grand Slam finale against England.

Henderson has earned his place

Andy Farrell's main selection call for this match concerned the second row with Iain Henderson coming in for James Ryan.

Dan Sheehan has taken the number two jersey back off Ronan Kelleher, but that isn't a great surprise. Sheehan is a world-class hooker and Ireland need to give him game time with a potential quarter-final on the horizon.

Ryan has been struggling with a wrist injury but Henderson undoubtedly deserves his place in the starting line-up. He was exceptional off the bench against South Africa. His line-out calling was impressive and he really stood up in the closing stages when Ryan and Johnny Sexton were both off the pitch.

When it comes to muscle, there's no better second row in the Ireland team than Henderson. He operates at an incredibly high level, and considering his fair share of injury worries in recent years, it's great to see him given this chance in such a big game.

Henderson has been Ulster captain for four years. He has leadership qualities in abundance and Ireland will be looking to him to demonstrate his calmness under pressure on Saturday.

The atmosphere for the South Africa game was absolutely immense and Saturday should be no different.Being in the Stade de France a fortnight ago reminded me of the second British and Irish Lions Test against South Africa in 2009 in Pretoria, which was among the most ferocious games I've ever been involved in.

It was a privilege to be in the stadium for Ireland's win over South Africa. Irish supporters had waited three years for that one and by the end of the night in Paris, they were all on cloud nine thanks to another heavyweight performance from Farrell's team.

But the Celtic rivalry between Ireland and Scotland runs deep. It goes back a long way and the Scottish fans will be out in force.

In that Six Nations game, the Scots really took the game to Ireland, shocked them a bit, and gave their supporters something to shout about.

Ireland took some time to find their stride against South Africa but laying down an early marker against Scotland could be crucial.

Scotland have shown in recent weeks how dangerous they can be. They play an attacking brand of rugby and have genuine matchwinners in Finn Russell and Duhan van der Merwe.

But if Ireland start strongly and build a lead in the first half, I am confident of an Irish victory and this journey being extended into the knockout stages and a possible quarter-final reunion with the All Blacks.

Tommy Bowe was speaking to BBC Sport NI's Matt Gault