Chelsea had looked on course to make it four wins out of four when Didier Drogba struck in the 82nd and 88th minutes to cancel out Sergio Aguero's opener for Atletico. However, Aguero curled home a brilliant injury-time free-kick to level the scores up at 2-2.
When asked if he was frustrated not to have won, the Italian said: "No frustration. It's not great to concede a goal in the last minute, but that can happen. We are in the next phase of the Champions League and this is important with two matches still to take place."
Ancelotti added: "That was a difficult match because Atletico played very well and I think the result is good.
"They put a lot of pressure on us in first half but I think we did well - not the best but it was good."
Drogba earned the headlines on his return to European action after serving a three-match suspension following an incident in last year's semi-final against Barcelona when he confronted Norwegian referee Tom Henning Ovrebo at the end of the game.
The in-form striker, who has scored nine goals in the Premier League already this season, returned in style though and Ancelotti was full of praise for the Ivory Coast international.
"Didier is an important player for us. We have a lot of important players but he is doing very well and we are happy," said Ancelotti.
When asked if he was currently the best striker in the world, Ancelotti replied: "I want to keep him and I don't to change him with another striker."