EDWIN van der Sar knows how much European nights mean to everyone at Celtic.

The former goalkeeper saw it for himself with Manchester United, as Shunsuke Nakamura’s iconic free-kick beat him back in November 2006 to help fire Gordon Strachan’s side into the last-16 of the Champions League.

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While the Dutchman lifted that famous trophy twice as a player, in 2008 with United and in 1995 for his first love, Ajax, he has re-invented himself as a chief executive with the Amsterdam club.

These days, what happens off the pitch in terms of revenue and finance is just as important to him as results on it. Like Van der Sar, Ajax have created a brand new identity with their Champions League exploits this season.

The stunning 4-1 defeat of holders Real Madrid in the Bernabeu helped Ajax earn millions of extra euros in prize money by reaching the last eight. But the penny only dropped that they had to change their playing fortunes 19 months ago on a torrid night in Trondheim.

Ajax were sent into a year in the European wilderness after they were knocked out of the Europa League play-off by Rosenborg. The only reason the Norwegians were there was that they had just been beaten by Celtic in the Champions League qualifiers.

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Ajax had actually reached the 2017 Europa League final just a few months earlier, losing to Manchester United. While that trophy will always pale in comparison to the European Cup which Ajax have won four times, following in Celtic's footsteps after 1967, Van der Sar would love to see both clubs retain a say in the future of the European game.

Celtic and Ajax have been adversaries since 1971 when Johan Cruyff and Co knocked out Jock Stein’s side in the last eight en route to their first success, with Celtic responding with a win in 1982. Martin O’Neill’s Celtic also defeated Ajax in 2001 in a play-off clash.

The clubs also met in 2013-14 in the Champions League group and the Europa League of 2015-16, with Van der Sar sitting in the directors box as ceo, which began his friendship with Peter Lawwell.

The pair share a vision of the future. Both are in charge at clubs who need the extra revenue from the Champions League. But both men know that Dutch and Scottish football is now marginalised by the wealthy European leagues and are scrambling to even get entry.

Ajax took a huge financial hit from last season’s Euro exile. In contrast, Celtic earned 32.5m euro, as some comfort for the maulings by Paris Saint Germain, dropping into the last 32 of the Europa League and elimination by Zenit St Petersburg.

The Europa League and unforgiving Champions League qualifying schedule has become familiar territory for both clubs. Ajax finished second in the Dutch league table last term to PSV Eindhoven and came through three qualifying hurdles before ending up in the group Celtic would have had had they beaten AEK Athens in the play-off round. Instead, Ajax were also joined in Group E by Bayern Munich and Benfica along with the Greek outfit.

“Celtic and Ajax are historic clubs, but that is why it is difficult not to be involved, they see the Champions League running away a little bit,” said Van der Sar, now 48.

“Celtic have done well in the last couple of years to reach the Champions League group stage. But for maybe 10 years it been harder to compete in the groups.

“It is not just Celtic, other clubs and countries [have similar problems]. It is getting harder and harder just to get there. We had to play three rounds just to get there. With Celtic coming from Scotland, they had to play four qualifying rounds this year, that’s tough.”

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Lawwell and Van der Sar work together at the European Clubs Association (ECA), an independent body representing over 200 clubs, trying to persuade UEFA to stem the tide of the six richest European leagues, who now have 20 of the 32 group places reserved for them.

The Dutchman believes that Celtic and Ajax are punished for the poor co-efficient of their respective leagues.

“Yes I think so," he said of their respective handicaps. "We want to raise the level of football in our countries but sometimes as a big club, you face the difficulties which come when the other clubs do not qualify for the group stage of the Champions League or Europa League and then dividing the points between all of the teams who got into Europe.”

Ajax rebuilt their European reputation by recovering from a Champions League elimination to reach the Europa League final in 2017, and Van der Sar endorses the second-tier European tournament, even if last season’s winners Atletico Madrid only earned 1million euro less than Celtic did.

“The Europa League is a great competition also,” said Van der Sar. “It is hard. But if you want to play European football and have ambitions, it is a podium where you can play and also meet the likes of Valencia. It was good for Celtic still to be there after January.”

It was being eliminated by Rosenborg last year that forced Ajax to turn to their youngsters. Midfielder Frenkie de Jong is on his way to Barcelona in June for 75m euro and others will follow.

But the fees which Ajax can command, such as 42m from Spurs for defender Davinson Sanchez, are sums which Lawwell and Celtic would be unable to match from any English suitors. History has taught us that.