Manchester City midfielder David Silva will miss Sunday's derby against Manchester United and could be out of action for up to a month with a knee injury, manager Manuel Pellegrini said Friday.

Silva was injured during the early stages of holders City's 2-0 League Cup defeat at home to Newcastle on Wednesday after a clash with the Magpies' Ryan Taylor.

"Manuel Pellegrini confirms that @21LVA will miss Sunday's game. Will be out for 3-4 weeks," City said on Twitter on Friday.

Premier League champions City have gone three games without a win in all competitions and could be nine points behind leaders Chelsea by the time they kick-off against United at Eastlands on Sunday if Jose Mourinho's table-toppers beat struggling Queens Park Rangers on Saturday.