Derek McInnes insists Rangers winning the Europa League would trump any domestic achievement.
The Kilmarnock boss reckons history proves tasting success on the continent is "far more difficult" than at home.
But he stressed the importance of Giovanni van Bronckhorst putting any form of silverware in the Ibrox trophy cabinet over the next week, be it in Europe or by winning the Scottish Cup.
Rangers will face Hearts at Hampden less than 72 hours after the final whistle in Seville and McInnes reckons that could be a problem for a squad already "stretched thin".
He wrote in the Mail on Sunday: "They've fallen short in the league yet still have such an exciting finish to the season in front of them.
"Ange deserves a lot of credit for banking two trophies. Rangers have stopped Celtic winning a Treble but now they must win something for themselves.
"And they still have the Scottish Cup to play for, too.
"The fact the final comes just a few days after Seville is potentially an issue. They will be facing a strong and motivated Hearts team and will do so with a squad that is already stretched thin.
"Win or lose, Rangers' achievements in Europe should not be underplayed.
"If they win this one it will supersede anything they could have achieved domestically.
"Because history shows it is far more difficult to win a European competition.
"I was brought up listening to my dad talk about the 1972 team. These Rangers players have a chance to engrain themselves not only in Rangers' history but that of Scottish football."
McInnes may believe Europe is the bigger fish but emphasised that Ange Postecoglou deserves enormous credit for winning the Double in his first season at Celtic.
He noted how the Parkhead boss was being urged to sacrifice his attacking principles during a difficult early period but stuck to his guns.
The former Aberdeen manager says being proven right will be extra satisfying for the Celtic manager.
McInnes said: "People have called Ange an idealist, said he needed to change when things weren't going well but he has committed to his style. Even early on, when results weren't coming, there were enough moments in every game that pointed to a clear plan.
"It's good learning for any manager, young and old, to follow your convictions and drive that message home. When you are as successful as he has been, it must be even more satisfying.
"Over the past few weeks, Rangers have had a chance to digest the fact that they were not going to win the league.
"At the outset, the big prize was Champions League qualification. Celtic have got that, the £30-40million. But this run means Rangers are getting a bit of that action, too, and they can join them in the big tournament if they beat Eintracht Frankfurt on Wednesday.
"But there will be disappointment at Ibrox that, having won their first title in so long, they have lost it again.
"The Europa League run has more than made up for that but the financial compensation will only come if they win it."
