French midfielder Petit has been nursing a knee complaint for some time while Nigerian left back Babayaro strained his hamstring during The Blues' 2-0 Champions League defeat to Besiktas last month.
Stamford Bridge doctor Neil Frazer said: "Manu has been playing with the pain and now needs to rest."
Petit's absence could mean a quick return to the fold for Argentine international Juan Sebastian Veron who revealed last week he asked Ranieri to axe him from the squad to play Middlesbrough so he could concentrate on working on his fitness.
Captain Marcel Desailly, who missed France's 3-0 demolition of in their final Euro 2004 qualifier, should be fit for Saturday's derby with Arsenal.
