The 25-year-old stopper's performance in the Champions League group game against the German champions was praised by the striker on Twitter and his Italian manager
Billed before the game as a "must-win" encounter by manager Roberto Mancini, the Citizens managed to walk away with a point after a last-gasp penalty from Mario Balotelli levelled the scores.
However, they had their keeper to thank for a string of fine saves, and Rooney believes there was only one reason why the game was not out of sight by that point.
"Have to say Joe Hart has been incredible. For me best keeper in the world," Rooney tweeted.
After losing their first group game 3-2 away from home against Real Madrid, picking up a positive result was required to keep the team in touching distance of both the Spanish champions and Jurgen Klopp's side, and Mancini was equally as effusive in his praise of the goalkeeper's performance.
"Joe Hart saved us from an incredible defeat," Mancini told reporters.
"He saved everything, so I should say thank you to him.
"He gave a fantastic performance. I don't know if it is the best performance in football history, but he did very well."
Manchester City currently sit third in the group now on just the one point from their opening two games, behind both Real Madrid on six and Borussia Dortmund on four, but they now face Dutch outfit Ajax in their next two fixtures.