That was the stark prediction from Light Blues legend and former German inter- national Jorg Albertz today.
Hoops boss Neil Lennon is hoping the Scottish champions can perform well in Europe's premier club competition in the future – starting next season.
In fact, Lennon, whose team stormed to victory in the SPL this season, has even revealed it is his ultimate dream to win the tournament as a manager one day.
"My ambition is to win the Champions League," he said earlier this month. "Is it poss-ible to win it here? Definitely."
Albertz, though, understands just how difficult it can be for a side from this country to compete against the cream of the continent's clubs.
The midfielder enjoyed some memorable, and successful, outings in Europe during his five trophy-laden years as a player in Glasgow.
He was involved in wins over the likes of Bayer Leverkusen, Borussia Dortmund, Kaiserslautern, Parma, PSV Eind- hoven and Sturm Graz during his five years here.
However, he was unable to help Rangers make it through to the Champions League knockout stages – despite playing in Dick Advocaat's expensively-assembled side.
Advocaat brought in superstars like Arthur Numan, Michael Mols and Giovanni van Bronckhorst in a spending spree that has since had catastrophic consequences for the club. And, in terms of conquering the Continent, it was all to no avail.
"Not going further in Europe was one of the big disappointments of my time here with Rangers," Albertz explained. "We had the players to do so and always fell short."
The former Bundesliga star – he played for Hamburg in his country's formidable top division on two separate occasions – felt the quality of domestic opposition hampered the Gers in the Champions League.
And he believes if Rangers go into liquidation – a possibility that looks increasingly likely in the wake of the 12-month transfer ban imposed by the SFA this week – and a newco is forced to start in the bottom division, then Celtic will struggle in Europe as a result.
Controversy has raged throughout Scottish football in recent weeks about the possibility of a newly-formed Rangers being fast-tracked back into the SPL this summer.
The vast majority of rival fans are incensed at the prospect of the Govan club avoiding the punishment handed out to Livingston and, before they ceased to exist, Gretna, for their financial indiscretions.
Indeed, even many Rangers supporters would like to see a newco start at the very bottom. They are far from enamoured at the penalties they will face if the SPL clubs agree to changes to their Financial Fair Play rules at an SPL board meeting on Monday.
Yet, the chairman of our top- flight clubs appear highly reluctant to lose the much-needed and significant income they currently bank as a result their involvement with the Glasgow giants.
There are very real concerns that Sky and ESPN will slash the current television deal, already substantially down on previous agreements, without Rangers' games to broadcast.
On top of that, there is the prospect of reduced income from season ticket sales and gate receipts at clubs without home games against the Govan club.
So the integrity of the league could be overlooked due to far greater fears over the standard of the game, players losing their jobs and other clubs going out of business.
Albertz also feels it would seriously impinge on this promising young Celtic side's chances of progressing into the group stages of the Champions League, never mind beyond, without four or more Old Firm in a season.
"I don't want to take anything away from the Scottish Premier League," added Albertz. "Celtic and Rangers have got a lot of decent players, but they don't play against good-quality opposition enough to excel in Europe
"If Celtic or Rangers could play every week against top-class opposition it would be different. They would become better players and better teams playing against a better standard of side all the time.
"The English Premier League clubs, for example, play top-class opponents every other weekend. Manchester City, Arsenal, Chelsea, Manchester United; they have difficult games against good teams nearly every week.
"Scottish clubs struggle in the Champions League because the sudden jump in standard is too great.
"The Old Firm game is the biggest and best fixture for Celtic or Rangers players in their domestic season. If you take that away, Scottish football will suffer.
"The quality of the league will decline and the transition to Europe will become far greater and more difficult to overcome."