South Korean software millionaire and philanthropist Ahn Cheol-soo finally announced he would run for the presidency, ending a year-long wait and throwing wide open a race that had looked to be a coronation for the conservatives' Park Geun-hye.
Vowing to tighten up on big business, which he has accused of treating employees like caged animals in a zoo, the youthful-looking 50-year old said on Wednesday he would create jobs for young people and share wealth and opportunities in the world's 13th largest economy.
Ahn has donated more than $200 million of his wealth to charity and is seen as the only candidate capable of derailing Park's goal of becoming South Korea's first female president, and the two are neck-and-neck ahead of the December 19 polls.
"The people have expressed their hope for political reform through me. I want to become the person who puts that hope into practice," a visibly emotional Ahn told a cheering crowd in a hall in Seoul, the capital.
Standing in front of a giant banner reading: "A new change chosen by the people is about to start", Ahn said he would push for political reform to open economic opportunities in South Korea, an Asian industrial powerhouse.
"The economic democracy and welfare policy that are being discussed currently must lead to economic innovation by combining growth momentum of our economy."
Ahn is standing as an independent and will need to cut a deal with the official opposition candidate Moon Jae-in to avoid splitting the anti-Park vote, although he did not offer an alliance in his speech on Wednesday.
Ahn has never held political office, while Park has lead the ruling conservatives and is the daughter of South Korean dictator Park Chung-hee.
She stood in as First Lady after the assassination of her mother in 1974 and only moved out of the presidential palace in Seoul after her father was gunned down in 1979 by his security chief.
The software entrepreneur turned college dean has broad support among people in their 20s to 40s and urban workers, who are likely to be the swing voters in the December polls.
"I believe the decisively important thing for sustainable growth is to build a welfare state," Ahn said in a book published this month.
He also said big business abuse of market power should be stopped, possibly by a new law aimed at regulating the chaebol, the family conglomerates that dominate the economy.
"I don't think we should be ambivalent about chaebol. We should introduce a 'corporate group law' to ensure they remain competitive but try to minimise their defects and abuses."
Ahn, a soft-spoken man of slight build with a trademark mop top haircut, founded the online security firm Ahnlab in 1995 after spending seven years developing anti-virus software while completing medical training and working full time as a physician in Seoul.
Ahn's "Youth Concert" tour last year that took him through college campuses was a smash hit with young people, with their combination of criticism of the political status quo and life lessons from someone who has had three successful careers.
Ahn portrays himself as an outsider, although critics note that he has been on the board of POSCO, a huge steel company, founded by Park Geun-hye's father in his drive to industrialise the then-impoverished country.
He faces questions over whether can prove himself a viable candidate due to his lack of political experience and whether he can withstand the bruising process of a high-profile campaign.
Half the people in a poll conducted in May said Ahn should not enter politics and more than two-thirds of them said he should remain a neutral bystander.
While he is seen as a liberal on many social issues, Ahn has vowed a tough stance on North Korea, which remains at war with the South after the 1950-53 Korean War ended in an armistice.
Both he and Park, whose mother was assassinated by a North Korean-backed assassin, have sought to distance themselves from incumbent Lee Myung-bak's hardline stance on the North.
"Some people ask what makes you think having run a small business prepares you to run an administration at a much bigger scale," Ahn said in an interview last year.
"I just laugh when I hear people say that ... I created something from nothing, I've overcome hardship."
(Editing by Jonathan Thatcher)