Former Chelsea coach Ray Wilkins has admitted that he is baffled by the club's transfer activity this summer and is "worried" about how the season will pan out.
Diego Costa's future is also shrouded in doubt as he is yet to join up with the squad amid reported interest from his former club Atletico Madrid and AC Milan.
"It wasn't the fact they lost yesterday to Arsenal because at times I thought there was some very good football from Chelsea. It was the body language the worried me, from Conte all the way down," Wilkins told talkSPORT.
"They didn't look happy. They didn't look a side that was united and I think they are in for a tough season if new faces aren't brought into the squad.
"I cannot for the life of me understand Nemanja Matic going to one of their biggest rivals in Manchester United. With Matic performing so superbly well over the last three seasons, I can't see why.
"I think Chelsea are weaker squad-wise. I think Conte should be worried and I think he looked worried yesterday. They need to be delving into their cash to bring more players in."
Conte and his men will begin the defence of their title on Saturday at home to Burnley.