The Argentina defender, who picked up a knee injury shortly ater signing this summer, finally got the chance to prove his worth in the game at Stamford Bridge.
"It's a weird feeling," Demichelis told the club 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
"I'm disappointed because we didn't get the three points. I think we showed good character, especially in the 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."
City take on Newcastle in the Capital One Cup fourth round on Wednesday,
with Demichelis confident they can get back to winning ways.
"If we keep playing like this, we're going to get a lot of good results," he
"I'm very happy in Manchester. I had a difficult start because I picked up an injury. It's not the best way to start when you join a new club.
"I worked really, really hard to be back soon. I'm a player with a lot of experience and I know injuries are a part of the game.
"I'm very happy to be back with my colleagues."