Thomas Tuchel has admitted the poor form of Kai Havertz and Hakim Ziyech meant he felt he had to make changes against Southampton.
Both players have struggled in recent weeks and were left out of the Chelsea side for Saturday’s 3-1 win at Stamford Bridge.
Speaking at his post-match press conference, Blues boss Tuchel said: “We always do our best to bring the players in the best shape but at some point after a lot of chances we have to admit that Kai and Hakim are not in their very best shape.
“It’s maybe not even their fault – it’s just like this at the moment. They struggle at the moment to be decisive.
“We had a period after pre-season when they were very decisive for us. They lost a bit of maybe belief or confidence.
“Nobody is angry at them and nobody has major concerns. But we have to pay attention to form.”
After back-to-back Chelsea defeats, and with Southampton known for their high pressing style, Tuchel instead opted to start with Ruben Loftus-Cheek.
Ross Barkley is another player recently back in the fold – he came on as a late substitute.
Tuchel explained: “I feel that at the moment Ruben and Ross have no pressure because they are happy to have these chances.
“Maybe they could not have imagined six weeks ago being in a position where they are actually getting important minutes.
“They can help us because they have this totally positive spirit and they don’t feel the pressure.
“We lost the last two games and we felt that something was lacking, so we decided to put Ruben because we were aware of the high pressing in midfield and still we wanted to go through midfield and to have Ruben and Kovacic who can not only pass but also drive with the ball to escape the pressing.”