Jose Mourinho says Chelsea's 3-0 romp over West Ham was the result of 15 days hard studying by the Blues boss.

Chelsea steamrollered a desperate-looking Hammers at Upton Park on Saturday.

And, for the first time since his return to Stamford Bridge, Mourinho's side adopted the tried-and-tested 4-3-3 formation that served the Portuguese boss so well during his previous stint at the club.

Asked about his decision to play three men in midfield, Mourinho said: “And (there were) four sometimes.

“It worked because West Ham has a certain style of play and we knew that it was very important to cope with the first long ball and the second ball.

“When you lose the first ball you are in trouble behind. When you lose the second ball you are in trouble to control the game and the possession of the game.

“So we tried to put more people in that area. The three plus Oscar coming to the middle too, tried to get the second ball and when you have the second ball play.”

The Blues boss said a lot of studying had gone towards what, in the end, looked like one of Chelsea's most comfortable recent performances.

He said: “I didn't have players to work for 15 days, but I had 15 days to study a lot, because I had nothing to do.

“I watched West Ham, I watched and I watched. And I tried to identify what they could do against us and play without a striker like they start, play with a striker like they did in the second half, where they normally win the second balls.

“We study a lot. When the players were back, no time to prepare the game by working tactically with them, but the game was prepared.

“Of course we had a good game and everything went well for us.”