SANTIAGO (Reuters) - Leftist independent Alejandro Guillier is tied with conservative Sebastian Pinera to win Chile's 2017 presidential race, according to a poll released Wednesday, further spicing up an election once expected to feature only establishment favorites.

Asked who they would vote for if elections were held on Sunday, 28 percent of respondents preferred Guillier, while 27 percent opted for Pinera, according pollster GfK Adimark. As the survey has a margin of error of three percentage points, neither candidate has a technical advantage.

"Regarding this year's election, spontaneous preferences in favor of Alejandro Guillier continue to be on the rise," Adimark said.

Until a few months ago, Guillier, a journalist-turned-senator loosely affiliated with the leftist Radical Party, was a relative unknown in Chilean politics. But graft scandals and sluggish growth in the world's top copper exporter have disenchanted Chileans with politics as usual and turned Guillier's outsider status into an asset.

In a December poll, Guillier was seen leading billionaire ex-president Pinera by five percentage points in a potential runoff, a likely scenario as both candidates are far short of the 50 percent needed to win outright in the first round.

Richardo Lagos, an investor-friendly ex-president once considered a front-runner for Chile's left-leaning Nueva Mayoria bloc, now trails far behind Guillier and Pinera with only 5 percent of the vote, according to the Adimark survey. Although the race features several other candidates, none of them have support of greater than 2 percent.

Adimark noted that the poll, conducted between Jan. 6 and 25, did not fully measure any political fallout from massive wildfires in Chile that accelerated toward the end of the month, destroying villages and consuming hundreds of thousands of acres.

Political risk analysts say the blazes could hurt the governing center-left coalition of current President Michelle Bachelet and boost Pinera's chances.

"The public has been sharply critical of the handling of the disaster, a further blow to the popularity of the incumbent center-left Nueva Mayoria coalition of President Michelle Bachelet," BMI Research wrote in a note to clients.

"This will further undermine the coalition's chances in November's general elections, in line with our view."

The Adimark poll surveyed 1,070 respondents, all by phone.

(Reporting by Gram Slattery; Editing by Lisa Von Ahn)