Massimiliano Allegri was left delighted by his players effort as the former Real Madrid man sacrificed himself for the good of the team.
The Argentinian found the back of the net, levelling after Robinho had given the home side a ninth-minute lead.
Robinho was assisted by Brazilian compatriot Kaka who showed another side of his game for much of the clash.
Kaka gave regular help to full-back Kevin Constant, as the defence looked to cope with the attacking trio of Alexis Sanchez, Neymar and Messi.
And having plied his trade in Spain for four years, Kaka knew the defensive work was necessary to stifle the Catalan club.
“I’ve played against Barcelona many times and I’ve understood the importance of their wide men,” Kaka is quoted as saying on ESPN.com. “Tactically, it was one of those games where we had to make sacrifices and I and [Valter] Birsa on the other side did that.
“Today, I needed to play as full-back. The coach knows where I like to play, but sometimes you've got to make sacrifices.”
The 2007 Ballon d'Or winner also showed glimpses of the Kaka that Madrid paid £56million for.
As well as assisting the Milan opener, the Brazilian made several breaks from midfield and looked neat on the ball.
And his performance certainly impressed his boss, with Allegri describing his showing as 'extraordinary'.
"“He played an extraordinary game,” Allegri said. “He showed what a champion he is. Yes, at times he even played as full-back - to be a champion, you don’t only have to be good with your feet, but also with your head.”
With Barcelona capable of tearing apart any side, the Milan manager also had praise for the team's performance as a whole.
“The lads played a good game and they conceded very little to Barcelona.
“We’ll try to get another good result at the Camp Nou, and then we have the most important games in the group to come.”
Milan currently sit second in Group H, and are two points ahead of third-placed Celtic.