1245 GMT November 21, 2019
The political newcomers swept aside the old guard in the first round, highlighting voter anger over a stagnant economy, high unemployment and poor public services in the cradle of the Islamic Awakening.
Adding controversy and suspense to the contest, presidential contender Nabil Karoui only walked free on Wednesday, having spent more than a month behind bars on suspicion of money-laundering, AFP reported.
This election is "more exciting than a local derby (football match)," said a young man taking part in lively debate on Bourguiba Avenue in central Tunis ahead of the showdown.
The vote, Tunisia's second free presidential election since the 2011 revolt, follows the death of former president Beji Caid Essebsi in July.
On Friday night, Karoui and law professor Kais Saied went head-to-head in a rare television debate, a last bid to woo voters.
Karoui, a 56-year-old business tycoon, appeared relaxed, if at times hesitant. Speaking in Tunisian dialect, he stuck to his key themes of economic liberalization and fighting poverty.
Serious but also at ease, 61-year-old independent candidate Saied called for the decentralization of power and criticized the country's partisan system, in classical Arabic.
The runoff outcome remains uncertain, with a ban on opinion polls, but Karoui received a boost with his newly formed party, Qalb Tounes (Heart of Tunis), coming second in legislative elections a week earlier.
Saied topped the first round in the presidential election, held on September 15, with 18.4 percent of votes, while Karoui followed with 15.6 percent. Turnout for that round was a modest 45 percent.