Former ophthalmologist and resistance fighter Abdullah Abdullah stands one step away from becoming the president of Afghanistan - the final part of a plan hatched five years ago, when he believes the job was stolen from him.
Abdullah, 53, has plotted to avenge defeat since the 2009 election when he came second to Hamid Karzai in the first-round vote and then dramatically pulled out of the run-off, alleging that fraud would again be used to fix the result.
Presidential candidate Abdullah Abdullah speaks to the media after casting his vote at a polling station in Kabul.(Reuters photo)
This time, he is the front-runner in the race and goes into Saturday's head-to-head vote after coming in an easy winner in the first round with 45 % compared to rival Ashraf Ghani's 31.6%.
As a pro-Western, religiously moderate politician, he has spent his time in opposition building ties with tribal leaders who hold the key to power, as well as staying close to the US and other major donor nations.
Abdullah, who started off as an eye doctor in Kabul, was a member of Burhanuddin Rabbani's government during Afghanistan's 1992-1996 civil war, and made a name for himself abroad for his fluent English and courtly manner.
His formative political experience was as the right-hand man to Ahmad Shah Massoud, the charismatic Tajik commander who led resistance to the Soviet occupation in the 1980s and to the 1996-2001 Taliban regime.
Massoud was killed two days before the 9/11 attacks on the United States, leaving Abdullah fearing that the anti-Taliban resistance would collapse.
But the US reaction to the strikes on New York and Washington transformed the landscape overnight, with the Taliban soon ousted and Abdullah emerging as foreign minister in the new government under Karzai.
Afghans line up to cast their ballot in Herat, Afghanistan. (EPA photo)
Mixed ethnic background
Abdullah used the post to give early warning to Washington that Taliban leaders ran the growing Afghan insurgency from neighbouring Pakistan - an issue that was dismissed until it became central to US foreign policy years later.
Born to a Pashtun father and a Tajik mother, he has long taken a strong stance promoting reconciliation between Tajiks and their tradition rivals the Pashtuns, the largest ethnic group in Afghanistan.
However, due to his closeness to Massoud, much of his core support still comes from Tajik and other Dari-speaking ethnic groups in the north.
In power, Abdullah would have to work hard to persuade Pashtun leaders that he is not beholden to his northern supporters.
His anti-Taliban record could also make starting a peace process with the insurgents more tricky.
Despite remaining embittered by the rampant vote-rigging by Karzai supporters in 2009, Abdullah has lately taken a conciliatory tone to the man he hopes to replace in the presidential palace.
"I would not go (down) the line that will be the politics of vengeance and revenge and retribution," he told AFP during the election campaign.
"Our priority of the future government will be to deal with the priorities of the nation."
Abdullah, a persuasive talker and elegant dresser, is married with three children.
On the campaign trail, he has delivered scores of professional -- if rather dry -- speeches at rallies and meetings, often raising the spectre of electoral fraud.
He claimed that cheating denied him the 50 % needed for a first-round victory in April, and it is hard to see him conceding defeat if the count is narrowly against him.
His double name reportedly emerged to placate Westerners confused by his single moniker "Abdullah".