Croatian fans were heading for Poland in droves to support their national side after their opening win against Ireland, travel agencies have said.
"A real sports euphoria was missing" ahead of the European Championship, that opened earlier this month and travel arrangements were sold mainly to corporate clients, said Nikolina Frklic, spokeswoman for the Atlas agency, told AFP.
"However, the situation has really changed" after Sunday's 3-1 win, she added.
National television estimated that some 15,000 fans were expected in Poznan, Poland, to support Slaven Bilic's side, who play their second Group C game against Italy on Thursday evening.
A special charter flight for the Italy tie was sold out while another for the match against Spain had only a few places left, Frklic said.
The one-day arrangement for Spain is sold at some 630 euros (792 dollars).