Austria championed Croatia's case during crisis talks between the EU and Turkey, putting up a ramp against the start of entry negotiations with the populous Muslim country unless they were also reopened with Croatia.
Talks were eventually opened with both countries almost simultaneously late on Monday.
"Danke Oesterreich" (Thank You Austria) was the headline splashed over one national newspaper, while others went with "Austrian Key to EU" and "Austria Backing Crucial for Croatia".
"Austria stubbornly insisted that the EU could not maintain double standards," said political analyst Stojan De Prato.
"You cannot sweep mass human rights violations in Turkey under the carpet and then put Croatia on ice because of one fugitive [General Ante Gotovina]."
Croatia was given the green light for membership talks more than a year ago, but the official start of negotiations was suspended in March, after the Balkan country's cooperation with the UN war crimes tribunal began showing signs of stagnation.
Chief prosecutor of the UN court, Carla Del Ponte, charged that Croatia was harbouring one of the tribunal's most wanted suspects.
However, Del Ponte changed her position on Monday, telling the EU that the Zagreb government was fully cooperating in the hunt for Gotovina.
The comments effectively cleared the way for entry talks to begin.
"The fate of the whole country was kept in the hands of one person. Now we can finally move forward to where we belong"
The long-awaited breakthrough was greeted with tempered joy, in contrast to April 2004, when an assessment that Croatia was ready for accession talks was welcomed with champagne, fireworks and a free pop concert in the main square of the capital, Zagreb.
"It's about time," said Vence Kero, a retiree. "The fate of the whole country was kept in the hands of one person. Now we can finally move forward to where we belong. Hopefully, I'll live long enough to see us in the EU."
The sentiments were echoed in the streets across Croatia, where frustration over delays in Croatia's path to EU membership caused support for entry into the bloc to sag to historic lows of under 50%.
Anticipation of a positive outcome on Monday lifted support over the halfway mark, independent polls indicated over the weekend.
Prime Minister Ivo Sanader shrugged off the polls recently, saying he expected a significant warming to the EU as soon as his government achieves more palpable results on the road to accession.
Sanader believes the country of 4.5 million will be ready for membership before 2008.