Ireland captain Johnny Sexton has warned his side they will be up against the best Scotland team of the Six Nations era when they continue the quest for a coveted Grand Slam at Murrayfield on Sunday.
Ireland, the only unbeaten nation left in this season's tournament, have dominated the fixture in recent years with 11 wins from the past 12 matches against their Celtic rivals.
Scotland, however, are enjoying a revival under coach Gregor Townsend.
They started this Six Nations with wins over England and Wales before a defeat by reigning champions France scuppered their bid for a clean sweep.
Nevertheless, a return to winning ways in Edinburgh this weekend would see Scotland secure a first Triple Crown since 1990.
The Triple Crown is the reward for winning all three matches against the other "home" nations - England, Scotland, Ireland and Wales - in the tournament.
"Definitely the best Scottish team we've played against," said Sexton. "Probably since the Six Nations started, it's the best Scottish team.
"It will be a really, really tough game and it will probably be our toughest of the championship so far."
Ireland have secured just three Grand Slams in their history, the last in 2018.
But they travel to Edinburgh on the back of bonus point wins over Wales, France and Italy.
"I spoke before the Wales game – if we lost it's Triple Crown gone, Grand Slam gone. Championship: you're under pressure straight away," said Sexton.
"We still have them in our grasp so we obviously acknowledge and talk about it and make sure that we deal with the pressure that comes with that but it's a privileged position to be going for it."
Furlong returns
Fly-half Sexton and centre Garry Ringrose, who both missed the round-three win in Italy, are back in the side after recovering from injuries.
Up front, prop Tadhg Furlong returns in place of the injured Finlay Bealham, having not played competitively since Leinster's 38-29 victory over Ulster on December 3 but has been passed fit following a calf issue.
Despite a 99-day gap between appearances, Ireland head coach Farrell had no qualms about Furlong's readiness for test rugby.
"Some players can and some players can't and he's across his detail like no other," Ireland coach Andy Farrell said of Furlong.
"Tadhg doesn't have to tear himself apart mentally to try and make sure that he gets up to speed because he's already figured it out."
Stuart Hogg will win his 100th Scotland cap on Sunday, with the 30-year-old full-back lauded as one his country's greatest players by Townsend.
"It's very well deserved," said Townsend. "He (Hogg) has been one of our best players over the last 10 years but also in the history of Scottish rugby."
Sunday's match has added significance because No 1-ranked Ireland and fifth-place Scotland have been drawn in the same group at the September-October World Cup in France with holders South Africa. Only two teams from each pool advance to the quarterfinals.
Although, with the talented Finn Russell leading at fly-half, Scotland have an attack to test any defence, Townsend was in no doubt of the scale of their latest challenge.
"It's the best Ireland team we've faced," he said.