Chelsea took the unusual step of publicly backing Jose Mourinho this week after a home defeat to Southampton left the champions with just eight points from eight Premier League games.
Mourinho insists he still has the support of his squad, a claim borne out by the public statements of John Terry and Cesc Fabregas in recent days.
Nike Tiempo V Soccer Cleats And now last season's top scorer Costa has laid the blame for Chelsea's shocking start squarely at the feet of the players - himself included.
Profiles Diego Costa
"We know we're not in the form we were supposed to be at the beginning of the season," said Costa, who has scored just twice in eight games.
"We need to blame the players because we came back from holiday very confident, thinking we could go back into how it was last season, and then realised the team was already in a bad situation.
"I'm going to be very honest: maybe a few weeks ago, five or six weeks ago, I was not on top of my game. At least physically. We talk within the players and we know that, maybe at the beginning, we were not 100 per cent as we were supposed to be when we got here.
Nike Magista Obra Soccer Cleats "I got injured at the end of last season and then I went on holiday. Maybe I got out of my diet and, when I came back, I was not the way I was supposed to be.
Nike Mercurial Superfly IV Soccer Cleats "I was a little bit overweight. That affected my game.
"You can be selfish and blame it on the manager but I'm not going to do that. I'm responsible 100 per cent, and so are the other guys. So all we can do now is train very hard and work very hard to try to get back to that level where we were the season before."
Nike Hypervenom Phantom II Soccer Cleats Costa also gave his manager a glowing reference, claiming "a million players" would want to work with Mourinho, Pep Guardiola or Diego Simeone above any other bosses.
He said: "I'm here because I'm happy with the manager but I'm not only speaking on my behalf. I am here to speak for everyone, for the group. All that matters at the end of the day is the group.
"I have spoken to all of the players and they all feel the same way about Jose. I don't like giving interviews, but I'm speaking for the group. We all feel the same way about Jose."
Nike MercurialX Proximo Street Cleats Costa has served a three-match ban for a clash with Arsenal's Laurent Koscielny and will be available when Chelsea host Aston Villa after the international break.
