Chelsea's Europa League campaign kicked off in style with a 1-0 win at PAOK Salonika on Thursday.
Maurizio Sarri made only five changes to the side that beat Cardiff at the weekend, and their dominance showed as PAOK's unbeaten record against London clubs came to an end at Toumba Stadium.
They took the lead with just seven minutes gone after Ross Barkley dribbled through the PAOK midfield and teed up Willian, who slotted home from close range to score his 20th goal in UEFA competitions.
Alvaro Morata had a good chance to double Chelsea's lead two minutes later after meeting Pedro's cross, but his header went just wide of Alexandros Paschalakis' goal.