Ireland's selection system makes them the "most cohesive" team in the world, according to England boss Eddie Jones.
The sides meet in round four of the Guinness Six Nations in London on Saturday (4.45pm, live on RTÉ) with both, after two wins and one loss to their names, still in the running for the title.
Ten of Andy Farrell’s starting XV against Italy came from Leinster with two more on the bench.
Although they will be without prop Andrew Porter for the game. He was subsequently ruled out for eight weeks by his club.
Stalwart Cian Healy, who also plays with the four-time European champions, may come in in his place.
The IRFU's de facto selection policy means only home-based players are in contention.
"It’s an important week in the tournament, there are three teams left in the tournament and we’re lucky enough to be one of those three," said Jones, whose side are third in the table behind Ireland and France.
"Ireland are favourites for the game, they’ve been in very good form in the autumn, they’re a very settled team, and very well coached by Andy Farrell.
"And apart from Andrew Porter I think they’ve got everybody available and ready to go.
"They are literally, and I say this without any hesitation, the most cohesive side in the world.
"The bulk of their team train together for the bulk of the year.
"So they are very well coordinated in their attack, they are very structured, they’re very sequenced in set plays, and they’re tough around the breakdown.
"So that poses a great challenge for us. But we’re looking forward to the challenge, we’re not intimidated by any team and we’re looking forward to playing against them."
Jones has been mixing up his selection this season and last, when they finished fifth, but the Australian insists they are on the right track for the World Cup next year in France.
"We're in a very good position mate, we’ve got a little over 12 months until we get together for the last part of the project," said Jones, who had added Bath flanker Sam Underhill to his squad.
"The three months before the World Cup is where every team becomes equal.
"We all have the same amount of time to practice, we all have the players the same amount of time.
"Up to now, teams have got their players for differing times, there’s different experiences.
"We can only have 25 players until Tuesday, other teams can have 42 until Thursday. So it’s all different.
"But once you get to the World Cup campaign start, it’s all equal. How are we tracking now? Yeah, in a really positive manner, mate.
"It’s not a perfect straight line, sometimes we’re going a bit quicker than others. And sometimes we’d like to go a bit quicker. But we’ve got great spirit in the side.
"Just look at the spine of the team - our 9, 10 and 15 - we played against Wales.
"They’ve got 12 times, 12 times the amount of caps we’ve got; 12 times.
"So what a fantastic experience for those young blokes, and to edge out a win against the Six Nations side [that Wales put out] is a real testament to where they are going.
"How much better are they going to be in 12 months with another 10 caps under their belt?
"The game is evolving and we feel like we’re in a really good position to take any opportunities there are to evolve our game in that position.
"And Marcus Smith, Harry Randall and Freddie Steward particularly have added to that mix."
Follow all of Ireland's Six Nations games via our live blogs on rte.ie/sport and on the RTÉ News App or listen to live radio coverage on RTÉ Radio 1. Watch live coverage of England v Ireland on Saturday 12 March (4.45pm) on RTÉ2 and RTÉ Player.
