Former Leicester City striker Gary Lineker says his old club "are on the edge of sporting immortality".
The Foxes, fighting relegation last year, are top of the Premier League with nine games to go.
They can go five points clear if they win their game in hand against Rafa Benitez's Newcastle on Monday.
"They are on the edge of sporting immortality," he said. "I don't think I have ever wanted something to happen more in sport in my entire life."
Writing for The Guardian, Lineker admitted he was wrong to be sceptical about the appointment of Claudio Ranieri, who succeeded Nigel Pearson as Leicester boss in July last year.
The Match of the Day presenter said he thought the 64-year-old Italian was an "uninspired choice" when he arrived after a spell as Greece boss.
"Oh how wrong I was," said former England captain Lineker. "How wonderfully, spectacularly, blissfully wrong."
Leicester were at the foot of the table with seven games remaining of the last campaign under Pearson, and Lineker says Ranieri has been "inspirational" in the club's rise from bottom to top.
"What we are witnessing, should Leicester go on to win the title, is quite possibly the most unlikely triumph in the history of team sport," added Lineker, who began his career with his home-town club.
"A collection of individuals who couldn't win a football match for love nor money a year ago have turned into an invincible force.
"A team with a spirit and togetherness the like of which the game has seldom seen.
"All beautifully held together by the canny, inspirational - yes, inspirational - Tinkerman."
Ranieri, who earned the nickname 'Tinkerman' while he was in charge of Chelsea as a result of his frequent squad rotation, has never guided a side to a top-flight title.
Lineker, part of an Everton team beaten to the title on the last day by Liverpool in 1986, has warned Leicester's current crop the pressure is about to rise.
"With expectation comes danger," added the 1986 World Cup Golden Boot winner. "They have, though, shown no fear thus far. No sign of wavering under the magnitude of what they might achieve."
The former Barcelona striker has witnessed more lows than highs in five decades as a Foxes fan, including attending an FA Cup final defeat to Manchester City and watching his boyhood club dip into League One as recently as the 2008-09 season.
But this Leicester side have lost just three Premier League games all season, compared to 19 last term.
"I watched Leicester City lose in the 1969 FA Cup final with my dad and granddad when I was eight and cried all the way home," said Lineker.
"I have seen them get promoted and relegated. I played for them for eight years. I even got a group of like-minded fans and friends to stump up a few quid to salvage the club when they went into liquidation.
"But nothing compares to this. Nothing. Things like this just do not happen to clubs like mine."