The underwhelming performance of the reigning champions will most likely require them to beat Rafael Nadal's Spain to stand a chance of reaching the knock out phase.
Gerard Pique boldly describes the inaugural edition of the revamped Davis Cup as a 'new era for tennis' but amidst all the glitz and glamour in Madrid's La Caja Majica there was only gloom for reigning champions Croatia on Monday.
Without their injured talisman Marin Cilic and with the team in upheaval after captain Zeljko Krajan was axed two days before their opening tie they drubbed 3-0 by Russia.
Borna Gojo lost to Andrey Rublev, Borna Coric was edged out by Karen Khachanov and they could not even manage a consolation point as Khachanov and Rublev combined to beat Ivan Dodig and Nikola Mektic in the doubles.
To make matters worse, the tie took place in a cavernous 12,000-seat arena with little of the fabled Davis Cup atmosphere Croatia could have relied on in either Zagreb or Split.
And to rub salt into their wounds, they will almost certainly need to beat Rafael Nadal's Spain in their second Group B tie on Wednesday to reach the knockout phase.
It was a bit different 12 months ago when Cilic fired Croatia to victory over France in a deafening din in Lille's soccer stadium.
That was the last final before radical changes to the historic team event, voted in by the International Tennis Federation (ITF) in 2018 in association with Barcelona soccer player Pique's investment firm Kosmos, came into effect.
The ITF has come under fire for meddling with the unique "home and away" format and replacing it with a soccer World Cup-style event featuring 18 nations, in one city, battling over seven days to be crowned champions.
Kosmos are pumping $3 billion into the ITF's coffers over 25 years and no expense was spared on Monday's lavish opening ceremony which featured a spectacular light show, dancers, drummers, violinists and an ear-pummelling DJ set.
The trouble was at 14:00 on a Monday afternoon in Madrid there were not many inside to watch the special effects.
A band of Croatian fans, complete with a brass band belting out "Viva Espana", whipped up some noise in a cavernous 12,000-seat arena that looked no more than half full when debutant Gojo and Rublev began the serious business.
But it went flat as Rublev won easily 6-3 6-3 before Coric played superbly to win the first set against world number 17 Khachanov but ended up losing 6-7 6-4 6-4.
The new format features 12 nations who came through the traditional February qualifying ties, last year's four semi-finalists and wildcards Britain and Argentina.
Organisers must get through 25 ties featuring two singles and a doubles rubber in seven days so two smaller stadium courts are also used at the venue and it was on those where a more familiar Davis Cup sound could be heard on Monday.
It was not quite Liege but a 100 or so Belgian fans roared on Steve Darcis, the man they call Mr Davis Cup, and David Goffin to victory over a well-supported Colombia team.
Over on Court Two, Canada's fans celebrated every point with a song as Vasek Pospisil beat Italy's Fabio Fognini before 20-year-old Denis Shapovalov stunned world number eight Matteo Berrettini to spark a red and white party.
Not all were won over by the new format.
"The only reason I came was because it's the last match for Steve Darcis," Laurens, from Liege said. "I won't come next year."
Belgium's supporters club president Pascal Giltaire said fans had originally planned to boycott the Madrid showpiece in protest at being deprived of their beloved home ties, only for 50 or so diehards to convince him otherwise.
"It's a good atmosphere but only because we are here," he said. "But without regular Davis Cup ties our club might die."
Despite some glitches and a few empty seats, however, it was an encouraging opening day for Pique's brave new world and Tuesday's evening tie between Spain and Russia, one of six on a packed schedule, might see the roof come off the Magic Box.