Ireland great Mike Gibson has described Johnny Sexton as "a phenomenon" ahead of this season's Guinness Six Nations Championship.
The 37-year-old will lead Ireland's quest for a fifth Six Nations title, but first since 2018, kicking off against Wales in Cardiff on Saturday.
Sexton looks likely to retire after the World Cup later this year, and Gibson has no doubt about the fly-half's continued influence on the Test team.
"He is a phenomenon," said Gibson, one of Ireland's greatest players, who won 69 caps and played in 12 British and Lions Tests during a stellar 16-year international career.
"He is a vital part of Ireland's success because of his decision-making and his influence, which is something he has demonstrated for years."
Ireland go into the tournament as the world's number-one team, a status underpinned by two away victories over New Zealand last year, a Six Nations Triple Crown and autumn successes against South Africa and Australia.
Head coach Andy Farrell has helped elevate the national team to new heights, and Gibson is among those looking on admiringly.
"It has been a wonderful time for us," he added.
"We have been successful against the All Blacks, successful also against South Africa and Australia, and these things make their mark on players.
"They can go out and say, 'I've beaten New Zealand, so I can deal with any side'. The quality of the Irish game has attracted spectators.
"They watch the quality of Leinster, and from an international point of view Farrell has been instrumental in allowing the side to play, to gain confidence, and the forwards are capable of dominating teams.
"We are number one in the world, which is something beyond dreams.
"The burden of being a favourite creates its own difficulties, but the expectation of the Ireland team is one of they can beat anybody. Everybody is making good sound decisions when they are in possession, which is key."
Farrell's influence has proved significant, and most pundits predict a Six Nations title race between Ireland and France this season, given their current domination of European rugby.
"The basics are done well – they are done at speed – increasing pressure on the opposition, increasing the intensity of your own play and taking advantage of every chance to score points," Gibson said.
"We have beaten New Zealand five times in the last eight meetings, which is astonishing.
"I think they have every reason to be confident and to be proud of what they have achieved. It is a wonderful period."