A cacophony of car horns sounded in the midst of a sea of red, gold and green national flags.
"
Today is party day
"
Mamadou Diallo
Senegalese fan
They congregated at the gates of the presidential palace.
Motor-cyclists drove up and down the streets shouting and waving flags.
One of them, Mamadou Diallo, told BBC News Online on his mobile phone: "Today is party day."
"Even if it is not declared a national holiday, no-one will work today."
"There are speakers playing loud party music on every street corner."
Muslim chants
The BBC's Chris Simpson in Dakar says that nearly everyone is wearing red, gold and green.
Some fans have had the traditional dress of "grands boubous" [long, flowing gowns] especially made up in the national colours.
Brightly coloured but dilapidated minibus-taxis sped into the city centre with fans waving flags from the windows and the rooftop.
"Come and touch the Serigne Touba, he brought us victory," shouted a youth holding out a picture of spiritual leader Cheikh Amadou Bamba, whose Islamic chants and prayers have been specially adapted by Senegalese football supporters.
"Senegal! Senegal!" the fans chanted, reports the French news agency, AFP.
Political football
"It's a real feat," one mother in Dakar told AFP.
Along with her four children, all clad in the national colours, she watched as hordes of joyous youths marched towards the presidential palace to celebrate.
President Abdoulaye Wade has been quick to associate himself with the success of the national team, the Lions of Teranga [hospitality].
He cut short a visit to President Jacques Chirac of France last year to join in the party when Senegal qualified for their first-ever appearance at the World Cup finals.
After Senegal beat France in the opening match, Mr Wade declared a national holiday.
But the fans in Dakar are not settling for the second round.
"We're unbeatable," said Mamadou Diallo.
"If we can beat France, we can beat England, we can beat Argentina" said another fan.