BUENOS AIRES (Reuters) - Argentina may be about to leap into the political unknown.

The South American country, the region's No.2 economy after Brazil, will vote in presidential elections on Sunday with a radical outsider, libertarian Javier Milei, in pole position to win, though he will likely face a second round run-off.

The wild-haired, chainsaw-wielding economist - who has risen from relative obscurity over the last year - came top in an August open primary and leads all opinion polls ahead of economy minister Sergio Massa and conservative Patricia Bullrich.

Milei, 52, is a poster child of Argentine voters' anger at inflation that may hit 200% this year, rising poverty levels and a sliding peso currency that erases the real-world value of people's salaries and savings. Many blame the political elite and have latched on to Milei's burn-it-all-down rhetoric.