The England midfielder came on for the home side with 17 minutes left for Raul Meireles, the Portuguese having cancelled out Mario Balotelli’s early strike, to win the match with a powerful penalty on 82 minutes.
The 33-year-old continues to be used sparingly by manager Andre Villas-Boas and revealed he is not finding it easy to adjust to watching from the bench so often.
“No I’m not [happy being on the bench],” the former West Ham United player admitted to Sky Sports. “It is not easy and I want to play.
“I’m at my best when I play regularly and was in a good run of form, scoring regularly, playing pretty well. But now I’m sort of in and out, but what can you do?
“I understand it with me being 33 now, but I know I’ve got a lot to give. I’ve got 18 months left here and I’ll be here for that long.”
Chelsea are now seven points off City at the top, but Lampard believes this defeat is not evidence of the league leaders' demise and still sees them as a major title contender this campaign.
He added: “Man City are the top team in the league this year, and quite rightly so due to some of the football they showed in glimpses tonight and more broadly over the season.
“Ten points is a big gap and luckily we've closed that.“I think the celebrations show what the result means,” he added in response to the players' visible delight at the victory at the final whistle.
“I had a little feeling really, in the second half especially. Despite the sharp way they started, once we kind of got into it I had a feeling it was going to be our night.”