Against Borussia Dortmund on Wednesday, Balotelli kept his nerve despite the importance of the occasion and goalkeeper Roman Weidenfeller's attempts to put him off.
Balotelli sent Weidenfeller the wrong way with a trademark dummy in his run-up to make it eight successes from eight attempts for City.
Hart still treasures the moment he saved a Balotelli spot-kick in training and his crazy celebrations made memorable viewing on YouTube.
But Hart, who was beaten by Balotelli in Italy's shoot-out win over England at Euro 2012, was convinced he would score on in the Champions League on Wednesday.
"Mario is never going to miss a penalty. I would put my life on him. He was cool and took it well. He handled the pressure. He always scores them," the Daily Express quoted Hart, as saying.
"I would put my life on him. He was cool and took it well," he added. (ANI )