Gary Cahill has admitted that Chelsea "were just not at the races" as they fell to a 1-0 defeat at West Ham United on Saturday.
The Hammers opened the scoring in the sixth minute through Marko Arnautovic and held on to their lead against Antonio Conte's side until the final whistle.
The result at the London Stadium means that Chelsea could finish the weekend 14 points behind Premier League leaders Manchester City, who face Manchester United on Sunday.
"We were well off it, we allowed them to get the early goal, we have been tight at the back recently and that was a poor one to concede," Cahill told Sky Sports News.
"We just didn't play our stuff. It's frustrating. We were just not at the races - for whatever reason that is. It's disappointing to come off and feel like that.
"I'm not one to make excuses. We do have loads of games - but if we played to our levels today we get something out of the game. But we didn't. West Ham of course deserve credit, but we didn't create as much as we can do."
Chelsea have now dropped 16 points in as many games, having dropped just 21 in the whole of last season en route to the title.
