Chelsea boss Graham Potter admits defeat at home to Southampton was a "step back".
Saints won at Stamford Bridge 1-0 via James Ward Prowse's free-kick.
Potter said: "I think it was (a step back), certainly in the first half, it was a below-par performance. Returning from the Champions League and we had to make some changes, so you lose a bit of fluidity and cohesion. Southampton set up with a plan, an idea. They mixed the game well with a big target man but our performance wasn't what we wanted in the first half and I take as much responsibility as anybody in that.
"I thought the response second half was good and I thought we deserved a goal, we created enough chances to score. But when you don't, then obviously it's difficult to win matches."
On taking off David Datro Fofana at half time, he said: To use Raheem [Sterling] really. We wanted to use Raheem in the wide areas and that was the decision. It was a tricky one for David I thought he had one really good action - and it wasn't a reflection on him. It was more tactical to use Raheem"
Asked about not using Reece James, Thiago Silva, Marc Cucurella, Hakim Ziyech and Ruben Loftus-Cheek, he also said: No injuries. More just the turnaround and demand of the games considering a few of them had injuries previously. With Reece, two 90s in a row, which is more than we expected at the start of the week.
"It was a case of managing the load and managing the squad."
Potter also insisted there was no dressing room row afterwards: There is no conspiracy, I can't give you that. There is a lot of media and I believe my colleague has done the media before me. I always come in and speak to you guys, understand the questions, and when we've lost 1-0 at home to Southampton, with the greatest respect to them, it is not good enough because of the results we've had recently.
"The first half is as much my responsibility as anybody's because the performance wasn't good. I thought the second-half performance was better and we deserved to score. If we do that, the game changes around. But 1-0 isn't good and we're disappointed with that."