That’s according to former Arsenal star and pundit Alan Smith.
The Spain international has been in fine form under Antonio Conte this season and has fired the Blues to the top of the table.
Costa leads the league in scoring, netting 13 goals this campaign.
But Smith reckons Conte’s side are too dependant on the 28-year-old.
“If they are to lose him for a period of time, they might struggle”
Alan Smith on Chelsea star Diego Costa
When asked whether Chelsea rely on Diego Costa too much, Smith told Sky Sports: “Yes, there is a danger of that.
“If they are to lose him for a period of time, they might struggle.
“Not just his goals but the way he leads the line and links up play.
“He occupies both centre-back’s with his movement.
“Costa is lethal at the moment and he gives everyone in that Chelsea team a great lift when they see him out on the pitch.”
The Blues have now won 11 games on the spin, conceding just two goals in that period.
Next up for Conte’s men is a home clash with Bournemouth on Boxing Day.