(CNN)Before Leicester City, there was Nottingham Forest. But there is one man that connects them both, with a foot in two of English football's greatest ever achievements.
Martin O'Neill: Leicester City 'can go a long way in Champions League'
Martin O'Neill, who is currently preparing to lead the Republic of Ireland at Euro 2016, was arguably Leicester's greatest ever manager before a certain Claudio Ranieri guided the Foxes to the English Premier League title in the Italian's first season at the club.
O'Neill was at the helm between 1995-2000, when the team still played at their old stadium on Filbert Street.
As well as getting the club promoted to the Premier League via the play-offs -- in his first season no less, as with Ranieri -- O'Neill also brought silverware to the side, in the guise of two League Cups, one of two England's knockout cup competitions.
Nearly 40 years ago, 35 kilometers up the road, in nearby Nottingham, an almost equally improbable success story was unfolding.
O'Neill was a midfielder in Brian Clough's Nottingham Forest side that shocked the established order in English football, by winning the top flight for the first time in the club's history -- just like Leicester -- back in the 1977/78 season.
But the fairy tale was only beginning: Incredibly, Forest won the European Cup -- subsequently rebranded as the Champions League -- at the first time of asking in 1979, and then retained their crown in 1980.
It was a story so good it simply had to be made into a movie, and the recent documentary, "I Believe in Miracles" faithfully relives Forest's glory days.
"I see a lot of parallels," the 64-year-old O'Neill tells CNN. "If you talk about the two center backs who are playing for Leicester City, Robert Huth and Wes Morgan, they remind me so much of Larry Lloyd and Kenny Burns.
"If Riyad Mahrez has really been their playmaker, I could compare him to John Robertson, who was absolutely brilliant for us. And Jamie Vardy up front [was] Tony Woodcock for us. Both strong defensively, and very strong on the break."
And what does O'Neill think Clough, who passed away in 2004, would have made of the Foxes' fantastic accomplishment?
"I know he's somewhere up there in the gods," quips O'Neill. "He would turn around and say, 'I defy Leicester City to go and win the European Cup twice, and until they do that, the achievement can't be considered as great.'"
Like many others, O'Neill is full of admiration for the way Leicester has turned the tables on the "very big clubs."
"What they've achieved is phenomenal. In this day and age, and the incredible money being poured into the football clubs, and seemingly the very best players in the world going to the top clubs, it's refreshing to see Leicester City assembling a team and winning a championship."
As recently as April of 2015, Leicester found themselves rooted to the bottom of the English Premier League, staring relegation in the face.
But a late run of seven victories in their final nine games didn't just save their season but marked the start of changing perceived football wisdom by becoming the 5,000/1 outsiders that went on to win the league.
Or in other words, to quote screenwriter William Goldman, who was referring to success in the film industry: "Nobody knows anything."
O'Neill is at pains to point out that the Leicester side he put together in the mid 1990's were more than competitive, and at least flirted with sustained success.
"We actually finished in the top 10 four times on the trot. We were never out of the top 10," he notes.
"We were beginning to build a side, when Celtic came calling to me in 2000. If we could have kept the side together, we could have tried to contest for the Champions League.
"That would have been a dream. But I don't think anyone in their right mind would have thought that Leicester City could have won the league."
Of course, this isn't O'Neill's Leicester any longer, but he continues to take a keen interest in them. And he's extremely bullish about the Foxes' imminent entry to the top table of European football.
"Although they're champions of England, and that's a great honor, I don't think they'll be any great expectation early on for them. I think if they make the second stages of the competition, and they could do that, anything could happen.
"The way they're playing, and the sort of form they're in, and the spirit around them, it's still possible to be able to go a long way in the competition."
In case O'Neill is interested, Leicester is currently 100/1 to win the Champions League.