Manchester City manager
The England number one produced several outstanding saves before Mario Balotelli struck a contentious late penalty to snatch a 1-1 draw in a pulsating Group D clash at the
Mancini said: "
Hart's performance drew high praise from his England team-mate - and Manchester United striker -
Rooney wrote on Twitter: "Have to say joe hart has been incredible. For me best keeper in the world."
Mancini was asked whether it was the best goalkeeping display he had ever seen.
The Italian said: "I don't know this. He did a fantastic performance, he was fantastic tonight. I don't know if it is the best performance in football history, but he did very well."
The half-time score could easily have been 3-3, rather than 0-0, as both teams looked to attack, but Mancini was disappointed by his side's efforts.
The result leaves it with just one point from its opening two fixtures in the competition and facing an uphill fight with back-to-back fixtures against Ajax to come next.
City has also still not kept a clean sheet all season and, despite Hart's brilliance, the defence is a concern.
Mancini said: "We didn't play well. We conceded a lot of chances to them and I am really disappointed by our performance.
"The Champions League is totally different from the championship. When you have a chance you need to score. If you concede like we concede this evening, it is hard to win.
"In the first half we had three or four incredible chances. If you don't defend, if you don't run like Borussia Dortmund did this evening, it is difficult.
"This is my problem - is my job. I will solve this problem."
City equalised in the last minute through substitute Balotelli after Neven Subotic was harshly judged to have handled at point-blank range as Aguero hooked the ball toward goal.
Mancini said: "It was important - Mario's penalties are like Joe in goal. He did very well.
"I am happy because he scored. Our performance was very, very poor, but at the end of the group this point could be very important."
Mancini conceded his team may have been fortunate to be awarded the spot-kick.
He said on Sky Sports: "He [Subotic] touched the ball with his hand. He was unlucky.
"It could be, maybe not - but I'm happy with the penalty."
Subotic was more forthright, feeling there was no way he could have got his arm out of the way.
The defender said: "Never, never, not a chance. I have a hand, I can't cut it off. It was never in my life a penalty."
Given the openings at either end, Dortmund coach Jurgen Klopp had mixed emotions after being forced to settle for a draw so late on.
He said: "Both keepers played really well, chances saved at both ends.
"I was really happy with my team's performance, I was really proud of them.
"I don't know when City last lost at home and we came really close.
"It was a deserved draw but when you concede a goal so near the finish it is hard to decide if you are happy with the point."
Further problems for City saw midfielder Javi Garcia limp off with a hamstring injury in the first half and talisman Yaya Toure also appeared to be struggling late on, although Mancini played down the latter's problem.
UEFA Champions League
Arjen Robben is desperate to bring an end to his own UEFA Champions League curse when Bayern Munich plays Borussia Dortmund in Saturday evening's (Sunday morning AEST) final at Wembley.