Chelsea boss Antonio Conte is adamant he trusts Diego Costa completely as the Premier League leaders prepare to take on Hull City.
The Spain international sat out last weekend's 3-0 victory at Leicester City following a reported disagreement over a back injury, with talk of a move to China gathering momentum.
Costa has returned to the match squad for Sunday's encounter, though, and Conte has little doubt the prolific striker is solely focused on Chelsea.
"Diego's focus and concentration is at the level I want. He is mentally ready to play," Conte told reporters.
"I can put my hands in the fire. What does it mean? In Italy, if you put your hands in the fire, it means you are certain 100 per cent. It means you trust the situation 100 per cent.
"If Diego is not concentrated and starts the game, the fault is mine, because I did not see it. I made my choice, and it would have been a bad choice. It would not be the player's fault, it would be mine because this week, I did not see that he was not focused or concentrating and was thinking about other situations.
"Every time Diego has played for Chelsea, he always put all of himself into it, for this shirt, for this club. I am sure that, if Diego starts, he will put all of himself into it for this club, the shirt and the fans, and do everything he can to win.
"Could the fans boo him? I do not think this can happen. It is not right. Last week, he had this injury. Now he is back. Together, we have to win. It is important for everyone to be focused: me, the players, the fans, because it is a really important game. Our fans are always important, they are great. They push us at home and away. For me, they are the 12th player."