Northern Ireland great Alex Elder was one of English football's quadruple pioneers and admits he's not surprised it's never been achieved.
The Lisburn-born star was a key member of the Burnley side that was the first to attempt the clean sweep of the First Division, FA Cup, League Cup and European Cup in 1960-61.
It was the inaugural season of the League Cup and the Clarets entered the campaign on four fronts after winning the First Division the previous year.
They fought on in all four competitions until losing to Hamburg in the European Cup Quarter-Final second leg on March 15.
They failed to win anything in the end, but went close with Semi-Finals in the FA Cup and League Cup, the Quarter-Final of the European Cup and finishing fourth in the First Division.
Current Premier League leaders Manchester City are the latest team to attempt to claim an historic quadruple and will be putting it on the line with their Champions League Quarter-Final first leg tie against Borussia Dortmund at the Etihad on Tuesday.
"It will be the best achievement of any club side in the world if they do it," said Elder (above), who won 40 caps between 1960 and 1969.
"They are playing unbelievable football. I know they've not won anything yet, but Pep Guardiola has people believing in something that I never thought was possible.
"In the end our run at the quadruple ran out of steam. We might have deserved to win something, but we didn't. That's football.
"We looked at it as new horizons. Burnley were used to just two competitions - the League and FA Cup. In 1960 we doubled that to four, and it was Europe that really excited us.
"We lost out to Hamburg, who had a left-winger called Gert Dorfel, who had scored two for West Germany against Northern Ireland, and it was like deja-vu with two more to put us out."
A few days later, with Burnley still smarting over their European exit, they lost to Tottenham in the FA Cup Semi-Final, with the north London club taking another step to their League and Cup double.
Elder believes that part of City's secret for their continued quadruple hopes in a chaotic and congested season is a reluctance to look too far ahead.
"Our manager Harry Potts had the same theory as City's Pep Guardiola in dealing with the pressure in going for the quadruple," he added.
"Harry told us to take each game as it comes. You keep hearing Pep say the same thing. We were not allowed to get excited. Harry kept our feet on the ground. We didn't really appreciate what was at stake.
"When you are in this position where the pressure mounts game by game, you need a manager who knows how to manage. It said a lot to me that before he signed his new contract, Pep didn't want to leave, the club didn't want him to leave and the players certainly didn't either.
"He loves his players and never publicly berates them. Harry Potts was like that and we'd do anything for him. We never called him our manager, he was our big brother. His door was always open if we had a professional or personal problem.
"Our Burnley side were not world beaters, but we grafted for each other. This City team are different. You can liken them to a refined racehorse. They have the talent, athleticism and strength in depth to win everything. They deserve to win the quadruple, I really hope they can do it."