The race between the two increasingly bitter rivals has been tainted with claims of fraud and ballot box-stuffing, most of it in favour of Karzai, whose camp has been claiming victory since shortly after polls closed.
The first results released from last week's ballot had put Karzai neck and neck with Abdullah, who led a strong campaign for change and has alleged that widespread state engineered fraud has damaged the vote.
Earlier James Bays, Al Jazeera's correspondent in Kabul, said Abdullah had lost his position a little but added that the situation could change when more than half of the ballots are counted by the weekend.
Afghan election officials said the final tally will be known only in September [AFP]
The final, certified results however are not expected until next month after an independent body clears hundreds of claims of electoral fraud.
The second-ever direct presidential election has been marred by Taliban attacks and simmering ethnic tension.
Already, 2009 has become the deadliest year for foreign troops since the US-led invasion eight years ago.
On Tuesday a massive bombing in Kandahar city in the south killed at least 43 people and injured 65 others in what has become the deadliest attack in over a year.
Analysts have said that a low voter turnout, one of the aims of the Taliban intimidation campaign, could raise questions about the legitimacy of the victor, and increase fears of unrest.