Johnny Sexton says the past 18 months have been a "dream come true" with Ireland as the Six Nations leaders prepare to face second-placed Scotland.

"From the start he's put a special environment together," said Sexton.

"He's one of the best - what sets him apart is his attention to detail, his philosophy on the game and how he manages to be himself."

Ireland go into the Murrayfield encounter five points clear of the Scots after winning their opening three games, though France's bonus-point hammering of England on Saturday means the Six Nations title will not be decided until the final round of matches next weekend.

Farrell replaced Joe Schmidt as Irish coach in 2019 and made Sexton captain while instilling a special atmosphere in the camp.

Ireland buzz

"It's an atmosphere that's been created by Andy - he's very different to the last one [coach], which had some amazing things about it as well," added the 37-year-old.

"We won championships under Joe but Andy came in and put his own stamp on it and changed the way we play, changed the way we approach things, changed the way we lead and changed the way we talk to each other.

"It took a while and definitely took longer than expected, although Covid probably didn't help that.

"Over the last 18 months it's been a dream come true for someone who's always dreamed of captaining Ireland and having success as an Irish captain. It's been pretty special.

"I was lucky enough to work with him on Lions tours in 2013 and 2017 and then as assistant with Ireland. To be the life and soul of the party and still be head coach, to still be friends with people despite not picking them - it's pretty unique."

Former Ireland head coach Eddie O'Sullivan believes Ireland's tactical acumen will prove crucial in what is expected to be a tight contest against the Scots on Sunday.

"These games come down to one thing only, namely which team is able to impose its gameplan on the other team on the day," said O'Sullivan.

"The tactics and the strategy on the day will be the defining factor.

"Ireland's gameplan should involve playing very direct rugby, very direct runners taking them over the gain-line like they did against Wales.

"Their tactical kicking has to be really good too, smart kicking to the back-field and getting off the line to slow down the Scots. If they get fast ball into the hands of Finn Russell that can cause problems."

O'Sullivan says the World Cup in September and October will not be foremost in the Ireland head coach's thinking with his side two wins away from achieving a first Grand Slam since 2018.

"The Six Nations isn't about squad development or squad rotation in any form, even in a World Cup year.

"Andy Farrell and everyone else wants to win a Grand Slam so there will be no risks taken with potentially losing a Grand Slam so that we are a bit wiser going to France in the autumn."