This Championship has been a long time coming for O'Connell, who was appointed captain by Joe Schmidt before the Autumn international series.

The Munster man missed all of last year's competition with a back injury, and only just made it to the Lions Tour of Australia.

"It's great to be back but it is hard work though, Joe [Schmidt] is fairly demanding when you're in camp," O'Connell said.

"There's a heavy workload with a lot to learn and a lot to be done, so there is no real time to have a bit of craic."

Ten years ago, Scotland were one of two sides the Irish could be almost certain of defeating – the other being Italy – but that's no longer the case.

Last year's Championship saw both teams beating Ireland under then-head coach Declan Kidney.

In the last four years, both Ireland and Scotland have shared the spoils and O'Connell knows it will be a tough test on Sunday.

"This is one of the best sides they have put out in a long time ... they have a lot of potential."

"We have watched a lot of last year's game, which was tough viewing. We watched an awful lot of their players as well – I think it's an excellent side and it will be a tough game." O'Connell said.

Even though the Irish squad went down the tunnel heartbroken after last year's loss to New Zealand, the standard set in that game's first half has raised expectations – which O'Connell argues is no bad thing.

"It's a great standard to have and it's a pity Scotland didn't come a week later," he said.

"You went away after New Zealand to the provinces for two months and played some high-intensity inter-provincial games, and you do have to switch off from Ireland and put your provincial hat on."

"Coming back in we are definitely two or three steps ahead of where we were when we first came together in November. There is a lot of experience in this team and it's up to us to make sure we capitalise on that performance and improve on it."