Portsmouth boss Harry Redknapp fears a big response from managerless Birmingham City on Saturday.
Redknapp told the club's official website: "It's always a dangerous game when teams lose a manager. They can be dangerous opposition and they'll want to come out and prove a point, so they'll be up for it.
"The crowd will be right behind them. St Andrews is an intimidating place to go and they're good supporters, so it's going to be a tough game."