Napoli looked set to move within two points of second-placed Roma as Marek Hamsik's header and a wonderful long-range strike from Gonzalo Higuain put Rafael Benitez's men into 2-0 lead at Stadio San Paolo.
However, Rodrigo Palacio reduced the arrears, before Icardi showed supreme confidence with a chipped penalty in the 85th minute after Fredy Guarin had been felled by Henrique - earning the full-back a second yellow card and subsequent red.
"Icardi is a brave guy," Mancini told Sky Sport Italia when questioned about the Argentina international's audacious spot-kick.
"I didn't even see the penalty as I wasn't looking.
"We were playing against a great side. We could not expect to dominate. It is also true that Napoli has great offensive potential and it is normal that they can get you in trouble in some moments of the game."
Icardi also spoke with reporters after the final whistle and explained that he opted for his cheeky effort because he is well acquainted with Napoli goalkeeper Mariano Andujar and felt his fellow Argentina international would have studied his previous penalties.
"I decided to take it like that because Andujar studies very well the attackers he faces," he said.
"We always want to win, but we gained a point which helps improve our league standing."
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