Sven-Goran Eriksson, Manchester City manager, has warned his players that Chelsea will "kill" them if there is any repeat of last weekend's horror show at Birmingham City.

City produced one of their poorest performances of the season - the worst was a 6-0 reverse at Stamford Bridge last October - as they slipped to a 3-1 defeat at St Andrew's, capping a disappointing run of form since the turn of the year.

"None of us - players or coaches - were happy about what we saw last Saturday," Eriksson said. "It was a poor performance and the players want to make amends against Chelsea.

"You have to stand up to Chelsea because if we don't stand up to them they will kill us. Not only in footballing terms, but physically they are very strong. I can't tell you that we're going to win or draw the game but I can tell you that the performance will be different.

"On Monday morning, we watched a video of the Birmingham game. We talked about it and nobody liked that - but we had to do it. If we're playing bad football then we have to try to get it right.

"Our approach to some games hasn't been as it should be and we have to change that. I think all the players agree that we have to do better."

Last October, one of the most pitiful surrenders in City's recent history saw them humiliated 6-0 by Avram Grant's men at Stamford Bridge.

That was a rare blip in an otherwise outstanding first half of the campaign, but City's customary fallibility has surfaced regularly since the end of 2007.

They have won only three times in the Barclays Premier League this year and their hopes of qualifying for Europe hang in the balance.

Eriksson admitted his side's display at Stamford Bridge was unacceptable. "That was a very, very bad performance from us and maybe the worst we've had," he said. "The approach to that game was completely wrong and maybe at that time we thought we were better than we were. At Stamford Bridge we played a very, very awful game."

Victory for City would be a massive boost to Manchester United's hopes of retaining the Premier League title at Chelsea's expense.

But Eriksson said: "We're more concerned with doing ourselves a favour. We have done a lot of good things this season but we've had a lot of unnecessary defeats as well.

"However, it's a long season and if we could get into Europe that would be very good."