Toulouse opened their Top 14 campaign on Sunday with a 26-25 victory at Bordeaux-Begles as the hosts missed three consecutive late penalties.
The visitors fought back from a 22-9 half-time deficit to lead, before clinging on in dramatic circumstances in the final 10 minutes.
Madosh Tambwe scored two tries and former Toulouse centre Remi Lamerat touched down in the opening period as Bordeaux built a commanding advantage despite three penalties from Toulouse's Thomas Ramos.
But Matthis Lebel and Romain Ntamack hit back with tries for Toulouse in the second half and a Melvyn Jaminet penalty put Ugo Mola's side a point ahead in the 67th minute.
Bordeaux still should have taken the victory, but France fly-half Matthieu Jalibert missed penalties in the 70th and 75th minutes after coming off the bench.
Toulouse back-rower Alban Placines was sent off with three minutes remaining for hitting Antoine Miquel.
But Bordeaux could still not find the three points needed to win, as Maxime Lucu's 45-metre attempt from the resulting penalty was also off target.
"The coach said at half-time that we would make changes straight away in the second half. It worked," said Jaminet. "The bad luck of the Bordeaux kickers also did us good."
On Saturday's opening day of the season, European Champions Cup winners La Rochelle beat Top 14 champions Montpellier 26-22, while last year's losing finalists Castres were beaten at Racing 92.