Liberia President Sirleaf welcomes run-off with Tubman
Liberia's President Ellen Johnson-Sirleaf says she is happy to be facing an election run-off against former UN diplomat Winston Tubman.
With almost all the ballots counted, Mrs Sirleaf gained the most votes but failed to pass the 50% threshold needed for outright victory.
Mr Tubman says he will contest the run-off after his party had alleged fraud and said it was pulling out.
This is Liberia's second election since the end of a 14-year civil war in 2003.
Mrs Sirleaf, who was last week awarded the Nobel Peace Prize, won the 2005 election to become Africa's first female elected head of state.
She defeated former footballer George Weah, who is Mr Tubman's running mate this time.
Mrs Sirleaf said she welcomed competition but was confident of victory.
With 96% of the vote counted, she has 44% against 32% for Mr Tubman, the electoral commission announced. Turnout was 71%.
"A run-off is imminent," said James Fromayah from the National Elections Commission (NEC). This has provisionally been set for 8 November.
The BBC's Jonathan Paye-Layleh says former rebel leader Prince Johnson is the potential kingmaker as he is running third with 12%.
"We want to thank the Liberian people," President Sirleaf told the BBC's Network Africa programme.
"We must go back to them and make a stronger appeal."
The election has been largely peaceful, however the headquarters of Mrs Sirleaf's Unity Party was on Saturday morning burnt to the ground in an apparent arson attack in the capital, Monrovia. It is not clear who was responsible.
The NEC, which is running its first poll, has rejected the accusations of fraud but Mr Tubman said the opposition threat to boycott the second round had prevented the NEC from declaring that Mrs Sirleaf had won in the first round.
On Saturday, opposition parties - including those of Mr Tubman and Mr Johnson - said they could offer photographs and witnesses to back their claims that the NEC had manipulated vote-counting in favour of President Sirleaf.
Her party said it was not surprised by the allegations.
"They are doing this thing because it is not going their way," said party secretary general Wilmot Paye.
Forces loyal to Mr Johnson infamously filmed the torture and murder of dictator Samuel Doe in 1990.
After the war, he became a born-again Christian pastor and was elected to the senate in the 2005 poll.
Our reporter says Mr Johnson enjoys strong support in his home region of Nimba County, the region with the second highest number of voters after the capital, Monrovia.
He has not yet said who he will back in the run-off.