Crowded aboard buses and trains, thousands more migrants flooded into Austria from countries unable or unwilling to cope with the wave of people escaping war and poverty for a better life in western Europe.
As several thousand more migrants arrived on Sunday in Austria from Hungary via Croatia, Budapest abruptly decided to reopen a border crossing with Serbia that on Monday sparked a surge of migrants into Croatia when it was closed.
The Horgos-Roszke 1 crossing is on the highway that before the migrant crisis engulfing Europe was the main route linking Belgrade and Budapest.
The closure added distance and uncertainty for thousands undertaking the gruelling journey across the Balkans into western Europe, with Croatia saying 25,000 had entered its territory in the past four days.
Within days of the border closure, Croatia said it could not cope with the flow and began to redirect the migrants back toward Hungary or toward Slovenia.
Croatia, Hungary and Slovenia are all EU members, but only the latter two belong to the passport-free Schengen zone.
The bulk of the migrants are fleeing the war in Syria, with the European Union receiving almost a quarter of a million asylum requests from April through June.
Germany alone expects up to a million asylum seekers this year.
On a train stopped at the Hungarian border town of Gyekenyes, across from northeastern Croatia, Ali Al-Mahmody waited with his wife and seven-month-old baby.
"All I want is to see my little baby boy grow up," the 59-year-old from Baghdad, who was imprisoned under Saddam Hussein, told AFP.
The family left Iraq about a month ago, and craves sleep, he said.
"We slept in forests in Macedonia. We can tolerate the hunger, but we just want to sleep."
The continent's biggest migratory flow since the end of World War II has caused a deep rift between western and eastern EU members over how to distribute the migrants.
The crisis has raised questions over the fate of the Schengen agreement allowing borderless travel across most countries within the 28-nation bloc, with several of them imposing border controls.