"Every team comes into this competition wanting to win a Grand Slam, wanting to win a championship and that's why it's so important to get off to a good start because it keeps everything alive," he said.
"I spoke before the Wales game - if we lost it's Triple Crown gone, Grand Slam gone, championship, you're under pressure straight away. Every team goes in with those aspirations.
"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."
Ireland have dominated matches against the Scots in recent years, winning 11 of the past 12 meetings.
But Gregor Townsend's side have impressed this year, beating England and Wales before defeat in France, and are bidding for a first Triple Crown since the 1990 Five Nations to keep themselves in title contention.
The Triple Crown is the reward for beating all three of the other "home" nations in any one tournament, comprising England, Scotland, Ireland and Wales.
"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 overcame the absence of a number of key players at the Stadio Olimpico, including their influential skipper, to remain as the competition's pacesetters.
Sexton could also achieve a personal milestone on Sunday as he is closing in on becoming the Six Nations' all-time leading points scorer.
But the Leinster man, who is just seven championship points short of former international team-mate Ronan O'Gara's record total of 557, said collective glory tops individual achievement.
"I'd rather not score another point and win a championship, win a Grand Slam than get the points record," he said. "It doesn't bother me too much. If it comes, fantastic, but it's not something I lose sleep over."