A rightward shift in the wealthy European Union member of 8.75 million people would be a fresh headache for Brussels as it struggles with Britain's decision to leave and the rise of nationalists in Germany, Hungary, Poland and elsewhere.
But all signs indicate that Austrians, fed up with a record influx of asylum-seekers, want to swap the gridlocked centrist rule for a more hardline government for the first time in a decade.
The People's Party (OeVP), rebranded by "whizz-kid" Kurz as a "movement", is forecast to reap more than 30 percent of the vote with pledges to go tough on migrants and easy on taxes.
The eurosceptic Freedom Party (FPOe) is battling for second place with the beleaguered Social Democrats (SPOe) of incumbent Chancellor Christian Kern.
Kurz - who as new OeVP leader forced the snap vote in May by ending the coalition with Kern - has yanked his party to the right and is expected to seek a coalition with the far-right.
Founded by ex-Nazis in the 1950s, the FPOe almost won the presidency last year and topped opinion polls in the midst of Europe's migrant crisis.
Then Kurz came along and stole votes with his hardline OeVP makeover, prompting FPOe chief Heinz-Christian Strache to call him an "imposter".
But Austrian media reported on Sunday that both parties were already involved in behind-the-scene talks, with the OeVP putting a "generous offer" on the table.
'Most important crossroads'
Meanwhile, the once-mighty SPOe could be flushed into opposition after their promising campaign suffered blunders and scandals.
Open dislike between ex-railway chief Kern, 51, and Kurz also makes any new attempt at ruling together seem unlikely.
But for some voters, the prospect of a far-right alliance is problematic.
"I'm not sure that we really need big changes," Tina Ernest told AFP at a Vienna polling station Sunday.
"I would say that in Austria we still live in paradise."
Kern, in office since last May, issued a final warning Saturday against a rightwing alliance, saying "Austria was at the most important crossroads in decades".
The OeVP and FPOe already shared power between 2000 and 2007. At the time the alliance with the far-right - then led by the late, SS-admiring Joerg Haider - ostracised Austria.
But there would not be the same backlash now owing to the "normalisation of the far-right in Europe since then," said expert Pepijn Bergsen at the Economist Intelligence Unit.
An 'Austria first' policy
Polls opened at 0400 GMT and close at 1500 GMT, with first estimates expected shortly afterwards.
Some 6.4 million people are eligible to vote in the closely-watched ballot which is expected to be a tight race.
"I'm feeling optimistic," OeVP party volunteer Michael Brandstetter told AFP in Vienna ahead of the vote.
"The way Kurz goes about things is what has captured people's minds".
For his turquoise movement, Kurz drew young candidates from outside politics and vowed to put "Austrians first" again.
As foreign minister, Kurz claims credit for closing the Balkan migrant trail in 2016, earning him praise at home.
Pushing far-right themes, he wants to cut benefits for all foreigners, slash Austria's red tape and keep the EU out of national affairs.
Experts say a rightwing government could turn Austria into a tricky partner for the bloc.
Vienna will hold the EU's presidency in the second half of 2018, just when Brussels wants to conclude Brexit talks.
"The Freedom Party as a government partner will not make a good impression in Europe (and) Kurz is aware of that," commented Der Standard newspaper in its weekend edition.
"But the question is whether there is any getting around Strache after this election."
By Nina Lamparski