Germany striker Werner has set a new club record of 94 goals before signing off at RB Leipzig, while Morocco winger Ziyech endured a frustrating end to his Ajax tenure with the Eredivisie shutdown due to the coronavirus pandemic.
Both high-profile new signings officially become Chelsea players on Wednesday, and Blues manager Lampard has admitted he could quickly integrate them into his existing squad in training.
"I am in the process of arranging plans now," said Lampard. "They are also in different positions in the fact that Hakim hasn't played for a long time because of the Dutch league situation and Timo finished at the weekend".
"We will formulate a plan for them that will look slightly different individually. We will decide in the meantime at Cobham in the training ground whether that means mixing with the squad or whether that means some physical work in the shorter term for themselves."