Mourinho: I never know if Costa is fit to play or not!

The striker was forced off against Barcelona and subsequently missed losses to Arsenal and Fiorentina, with the manager admitting even muscle scans are not conclusive Jose Mourinhohas admitted that Diego Costa's continual hamstring problems are becoming a concern for Chelsea. The striker missed Sunday's Community Shield loss to Arsenal before sitting out Wednesday's home defeat to Fiorentina as the Premier League champions pre-season preparations ended with a whimper. Costa made just seven league outings from February onwards after suffering niggling setbacks to a long-standing injury, but Mourinho has revealed even scans do not show any damage. "Costa is not ready. It is not a good feeling for him, it is not a good feeling for me," Mourinho told reporters. "I have to be honest and say that it is a bit of a concern. A player that didn't finish the season and [then] doesn't start the season obviously doesn't make me happy. "The boy is trying hard but he has a problem against Barcelona [last Tuesday]. The scans show there is no injury so next day he trains, but the next day he is not comfortable. Then, 24 hours before the [Community Shield], we don't know if he plays or doesn't play. Mourinho added: "I won’t risk my reputation again. You asked me before last weekend and I told you he was ready to play. He wasn’t. I don’t know. I don’t risk saying yes, and I don’t risk saying no. On Friday at the next press conference I think I will tell you again that I don’t know." Chelsea host Swansea City to Stamford Bridge on Saturday as they start the defence of their league crown, with Radamel Falcao or Loic Remy expected to lead the attack.