Senegal looked headed for a second round of voting in a fraught election in which President Abdoulaye Wade is seeking a disputed third term, local media and opposition candidates said Monday.
However the 85-year-old leader's camp warned it was too early to note a significant trend.
Former Wade protege Macky Sall, an ex-prime minister, is making a strong showing in unofficial results trickling in from polling stations.
"The figures in our possession, published in the media, and the trends from polling stations show that a second round is inevitable," the 51-year-old said in a statement published on his website.
"We have won the biggest departments in the country. We have won in each of the four departments in the Dakar region.
"I warn the sorcerer's apprentices against any attempt to confiscate the people's will. The massive rejection of the outgoing president has been shown in the results."
Sall is taking part in elections for the first time.
The mayor of the western city of Fatick fell out of favour with his former mentor Wade in 2008 after serving in several ministerial portfolios and as prime minister.
The country has been in suspense over who the main contender will be in a wide-open field of 13 opposition candidates, with Sall named among three other big guns as the best placed to take on the 85-year-old incumbent.
However El Hadj Amadou Sall of the incumbent's campaign team warned there were "no heavy trends" and nothing indicated that there would be a second round of voting.
Wade is seeking a third term in office after circumventing a two-term limit he introduced into the constitution. He says changes extending term lengths from five to seven years made in 2008 allow him a fresh mandate.
The country's highest court upheld his argument which sparked a month of riots in one of Africa's most stable nations, leaving six dead.
The defiant leader was roundly booed as he cast his ballot at his own polling station on Sunday, where early results show he was trounced by another former prime minister, Moustapha Niasse, with Sall placing third.