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.
The Spain international continued to trouble the PAOK defence, running on to the end of an Antonio Rudiger through ball, with his shot inches away from finding the net.
Marcos Alonso found Pedro with a low cross from deep shortly before half-time, but was unable to beat Paschalakis.
The second half began with plenty of Chelsea half chances but without much threat, while PAOK offered little in attack themselves.
Morata's search for a goal went on and he found the back of the net with 69 minutes on the clock, but he was adjudged to have been offside following Pedro's pass.
A red card could have been distributed in stoppage time after Antonio Rudiger slapped Amr Warda's hand, who then retaliated by grabbing the German international's throat, but both were only booked for the altercation.
Pedro was forced off with a shoulder injury after colliding with Paschalakis, and Chelsea held on to secure their first three points of the group stage.