"The initial objective was to be ahead of Nigeria going into the final two games," the Valenciennes player told FIFA.com. "We are in that position now and having put in so much effort, we can't let it slip."
The equation for the Carthage Eagles is a simple one: beat Kenya and Mozambique and a ticket to the 2010 FIFA World Cup South Africa™ is theirs. And should the Super Eagles drop points at home to the Mambas on Sunday, Ben Khalfallah and his team-mates could even be celebrating qualification a game early.
"We're trying to put all that to one side but it's tough to keep it out of our minds," explained the sports management graduate, who broke into the national side just over a year ago, before the African Zone, Round 2 game with Burkina Faso.
"It would be fantastic to do it in front of our own fans but we need to stay calm because it's never easy to win a qualifying match in Africa. Our match away to the Kenyans, who are a very physical side, was a terrific battle."
Humberto Coelho's team have not tasted defeat in the qualifying competition since losing at home to Paulo Duarte's Stallions in their opening match in Round 2. "Everyone learned the lesson of that setback," continued Ben Khalfallah, who started his club career with Amiens in his native Picardie.
In the 15 months since that reverse to Burkina Faso, the Tunisians have collected six wins and three draws in nine matches, a run that has filled them with confidence going into the final straight. "Tactically and defensively we have got things right. Coelho has instilled his discipline and we've just picked up the winning habit from there."
"A lot of the team are playing in Europe and the ones playing in the national league are with the top three clubs, so they're used to winning every weekend," said the 26-year-old, now in his second season in Ligue 1.
That impressive unbeaten run features last month's crucial 2-2 draw in the Nigerian cauldron of Abuja, a result secured thanks to a late equaliser. "We had to be very strong mentally in that game," he explains. "It was hell playing down there and getting an equaliser like that at the end of the game showed just how much character we've got."
Coelho, who took Portugal to the semi-finals of UEFA EURO 2000 before enjoying spells with Morocco and Korea Republic, has been central to the recent revival in Tunisian fortunes. Since taking over from Frenchman Roger Lemerre, the man who steered the class of 2004 to success at the CAF African Cup of Nations, the experienced Portuguese has revitalised a side deflated by two consecutive failures in the continental championship.
"He's turned to a new generation," said Ben Khalfallah. "A lot of the players have only been in the national side for a maximum of two or three years. Coelho wanted to bring an end to an era, turn the page and start again by applying his own principles. And it's been a good thing if you ask me because I've become an established member of the team in just a year and a half."
New-look they may be, but Tunisia still have the weight of their footballing heritage behind them, a heritage that includes four FIFA World Cup appearances, the last three of them on the bounce.
"We're not scared of missing out," said Ben Khalfallah. "We'll have the fans behind us against Kenya and I'd much rather be in our position than Nigeria's."
Ben Khalfallah and his fellow Carthage Eagles have already embarked on the final stage of their South Africa 2010 mission with a training camp in the city of Sousse, an indication of just how important the Kenya showdown is to their FIFA World Cup aspirations.