Tunisian police deployed more than 6,000 officers as well as drones and canine units for a hotly anticipated CAF Champions League final on Friday after a controversial first leg.
Between 50,000 and 55,000 fans are expected to pack Rades stadium in a southern suburb of the capital for the battle between Tunisia's Esperance and Al Ahly of Egypt.
Ahly, bidding to win a ninth continental crown, enter the second leg holding a 3-1 lead after a stormy first leg on November 2 in the Egyptian city of Alexandria when they converted two disputed penalties.
"The last time the stadium was so full was before the 2011 revolution... But all preparations are in place, we're ready," National Security spokesman Walid Ben Hkima told AFP.
He said metal detectors had been installed for the first time at all gates into the ground and extra security measures taken to protect Ahly players and staff and the 2,000 to 3,000 accompanying Egyptian fans.
Tunisian Prime Minister Youssef Chahed met this week with officials of Esperance and the country's football federation to discuss match security.
Esperance coach Majdi Traoi told a news conference on Thursday that he had "great faith in the supporters" of his club and did not expect trouble.
At a semi-final match last month between Esperance and Primeiro Agosto of Angola, clashes between police and fans left 51 people injured and led to 12 arrests.
Tensions have run high since the death in March of a young supporter who drowned near the Rades stadium after being chased by police. An investigation was opened and 17 policemen have been charged in the case.