Gary Cahill was left frustrated by Chelsea's lack of luck as their disappointing start to the season continued with a 2-1 defeat to West Ham.

Mauro Zarate put Slaven Bilic's side ahead before Nemanja Matic was dismissed for picking up a second yellow card, with Jose Mourinho also sent to the stands during half-time.

Cahill scored an equaliser for Chelsea after the interval but Andy Carroll's late header ensured the three points remained at the Boleyn Ground.

Mourinho's side also had a goal from Cesc Fabregas ruled out for an offside decision and a Kurt Zouma header cleared off the line by Manuel Lanzini in the first half.

Some of the officiating left the Chelsea centre-back confused and frustrated, and he admitted his team-mates are suffering as a result of their ongoing struggles.

"[The mood in the dressing room] is not great, like you would imagine when you lose games. Last season we weren't used to it. The lads are devastated," Cahill told BBC Sport.

"You are left scratching your head sometimes. In the first half, the Cesc Fabregas goal could have been given and we had the goal that was nearly over the line. That sums up the way we are going.

"And then we've got the sending off. Originally we played on – we thought the referee had played on. Maybe the assistant called it back – I'm not sure what's happened there.

"We've not had the rub of the green but we're not feeling sorry for ourselves. We have to work hard to turn this round.

"Not many words are being said at the moment. I'm sure we'll reflect in next day or so.

"We worked really hard at 10 men and had the majority of the play in the second half. It's a summary of our season at the minute."