Frank Lampard could face Chelsea for the first time since leaving Stamford Bridge in the summer .
Pellegrini said the 36 - year - old , his former club 's 211 - goal record scorer , has done nothing wrong in signing for City .
Frank Lampard could face Chelsea for the first time since leaving Stamford Bridge in the summer but Pellegrini said the 36 - year - old , his former club 's 211 - goal record scorer , has done nothing wrong in signing for City .