Chelsea manager Jose Mourinho gave his side a mark of 'minus one out of 10' for their first-half performance in the 2-2 draw against Newcastle.
Mourinho saw the champions improve to come from two goals down and earn a point but was livid with their display in the first 45 minutes.
He said: "In the first half, from 0-10, we were minus one. It was that bad.
"We were so poor, so bad. At half-time I said I was sorry I only had three subs as I wanted to change six."
Goals from Ayoze Perez and Georginio Wijnaldum put struggling Newcastle 2-0 up at the hour mark but Chelsea rallied, as goals from substitutes Ramires and Willian earned a point.
Willian's late free-kick denied Newcastle their first win of the season and Mourinho said he will now try and understand what was behind their lethargic first-half showing.
"In the second half we played very well," Mourinho said.
"Ramires and Willian moved the game, they brought more intensity, were much more dynamic. Newcastle could not cope with it.
"I have to try to understand why they can play so bad in one half and so well in the other. We were bad in every aspect of the game in the first half..
"Too many poor individual performances and it was impossible to be a competitive team."