Manchester City manager Roberto Mancini says striker Carlos Tevez will be out of action for about four weeks because of a hamstring injury, ruling him out of Saturday's FA Cup semifinal match against Manchester United.

The former United striker was substituted because of the injury in the 16th minute of Monday's 3-0 Premier League loss at Liverpool.

Mancini says the injury "is a big problem but we can't take any risks."

Tevez has scored 42 Premier League goals in 63 appearances for City, with another nine in 12 matches in domestic cup competitions.

United and City meet in the first of two semifinals at Wembley. Bolton and Stoke meet in the second match on Sunday.