The Argentine played his first match since recovering from a knee injury on Sunday during City's 2-1 defeat at Chelsea in the Premier League.
Despite the disappointing result, Demichelis admits that he is pleased to be back to full fitness following a spell on the sidelines.
"It's a weird feeling," the 32-year-old told the club's official website. "I'm sad because we lost the match in the last minute, (but) it's great to be back on the pitch; I'm very happy to make my debut for City.
"I'm disappointed because we didn't get the three points. I think we showed good character, especially second half.
"It's not easy to come to Stamford Bridge. We played really well in the second half and we showed how we want to play."
The Blues can get back to winning ways on Wednesday night when they travel to Newcastle United in the fourth round of the League Cup.