Sweden international Sebastian Larsson has started talks about a contract extension at St Andrew's.
The 24-year-old former Arsenal midfielder has played a key role in City's excellent recent run and has already scored 21 goals in 144 appearances for the club following his arrival, initially on loan, in the summer of 2006.
"We are in negotiations with Birmingham, but I am trying to focus on my football," Larsson told Expressen.
"We are playing with confidence and it's really fun to play football right now.
"Our confidence is very high and that makes you grow as a team. We believe in what we do and work hard for each other."
Larsson eventually sealed a permanent £1million switch from the Gunners to City in January 2007.