Jose Mourinho reckons Diego Costa is unstoppable and admits even he sometimes has difficulty standing in the way of Chelsea's new goal machine.

Costa left Stamford Bridge on Saturday with the crowd singing his name having netted a record seven goals in his first four Premier League games.

And Blues boss Mourinho puts so much of the Spanish striker's success down an aspect of his personality which refuses to be told what he can and cannot do.

“The most important thing of a players character is what effects his performance as a player,” said Mourinho.

“The fact that (Costa) was a risk and a doubt before Everton, a risk and a doubt before the Spain game (against France), a risk and a doubt before (the Swansea) game - and he played all three games.

“He is a risk and a doubt again for next Wednesday (at home to Schalke) because of an accumulation of matches - but nobody can stop him.”

Asked if Mourinho had tried he said: “I tried, I tried to be sure. To be 100 per cent sure - but he goes. He is a fantastic character.

“If the injury is a clear injury of course (I can say he can't play) - yes. But when the doubt is there and he has not the best feelings but he feels he can - he goes.”

Mourinho said this was a rare asset he had discovered in Costa similar to that found in John Terry, where he is willing to sacrifice all for the team.

“It is not about the modern player, it is about the modern society,” said the Blues' boss.

“The education they get, the people they have sometimes behind them to make them be a little bit more selfish in the sense of 'you first and the team second'.

“This concept of the team first and me second (is often lacking). The team needs me and I am ready to go for the team.

“I am not saying it is an old fashioned concept, no way but in this moment when you get guys with this mentality (like Costa) they become special and they can be an influence to the people around them.”

Chelsea face German side Schalke in their first Champions League group game this Wednesday at Stamford Bridge.