Chelsea goalkeeper Petr Cech insists Manchester United will feel the strain of their bid to win an unprecedented quintuple.

Chelsea, who were on course for the quadruple in 2006-7 until early May but then had to settle for the Carling and FA Cups, narrowed the gap on United at the top of the Premier League to just four points with a hard-fought 1-0 win over Portsmouth at Fratton Park on Tuesday night.

Cech said: "It's hard when you want to win every competition -- we know because we have gone close before. You can have a bad day and sometimes it's not even that, it's just bad luck. Sometimes you hit the woodwork three times and then concede at the other end and you're out of a competition."

He added: "It is always tough. You need to have everything going for you, the momentum and luck to achieve it. It's hard."

Chelsea winger Salomon Kalou is happy to remain at Chelsea despite saying he would love to play under Arsene Wenger at Arsenal.

Kalou was approached by Wenger last summer and claimed it would be a 'dream' to play for the Gunners. But the Ivorian has now clarified his situation

"I am very happy at Chelsea," he said. "For the moment, I'm playing well and I don't see why I would be leaving.

"There are two years left on my contract and I'm happy at Stamford Bridge. Everyone supports me - the fans, my team-mates and the staff. So I don't see why people have been worried by these rumours."