Chelsea boss Jose Mourinho has insisted that the club needs to sign another striker during the summer transfer window.

The Blues are already a forward down following the departure of Didier Drogba, with Mourinho stating that the Stamford Bridge outfit will require three top-level strikers to be strong enough to retain their newly-claimed Premier League crown.

"We have to buy a striker because we want to have three strikers of a good level. We do not want to have just one [summer target]. Then you lose a good position on the negotiation table," Mourinho told The Sunday Times.

"It will be difficult to find players to go straight into the team. Because it's not easy to find a better striker than Diego [Costa], a better keeper than [Thibaut] Courtois, a better midfield player than [Nemanja] Matic or [Cesc] Fabregas.

"This season is about improving the squad, bringing players to make us more consistent, so we don't go through difficult periods like last season when we had crucial injuries. We have to try and protect that situation by adding two or three players."

Chelsea claimed the title last season with 87 points.