City looked set to slip to their third defeat in four matches in all competitions when Andre Schurrle turned home Eden Hazard's low cross in the 71st minute after Pablo Zabaleta had been sent off for a second bookable offence.
However, Pellegrini's depleted team rallied and earned a share of the spoils five minutes from time through substitute Frank Lampard, who found the net against the club he left at the end of the season.
Afterwards Pellegrini was quick to criticise Chelsea for what he felt was an overly defensive approach, accusing Jose Mourinho's men of playing like a "small team".
But, while the Chilean was angered by the visitors' tactics, he had nothing but praise for his players, earmarking midfielder James Milner and debutant defender Eliaquim Mangala as stand outs.
"I think that we had the best performance as a team during this year, including [in the 3-1 win] against Liverpool," Pellegrini said.
"When you have a good performance as a team it's because you have players with a high performance. Every time Milner plays he always does well, he's a very important player for us.
"Mangala's first game here and he didn't have much work to do but every time he had a challenge he won it, which is important for us because we play with a lot of space behind our defence."
