Willian's early goal was enough for Chelsea to beat PAOK Salonika in the Europa League and maintain their winning start to the season.

The Brazilian returned to the side for Chelsea's first Europa League game since winning the competition in 2013.

And he sidefooted home from Ross Barkley's lay-off in front of a raucous sold-out crowd in their Group L opener.

Alvaro Morata and Pedro missed chances to make the win more emphatic as Chelsea dominated in Thessaloniki.

Chelsea's victory - their sixth in a row this season, after a Community Shield defeat against Manchester City - puts them on three points in Group L, level with BATE Borisov of Belarus who won 2-0 away at Hungarian side Vidi.

Chelsea's strength in depth
Having made five changes from Saturday's 4-1 win against Cardiff, the way Sarri's side controlled virtually all of the contest suggests they have a squad capable of mounting a serious challenge at home and abroad this season.

Eden Hazard, who Sarri says has complained of tiredness twice in the last month, was rested along with David Luiz and Mateo Kovacic.

And it was Willian, who came off the bench to seal Saturday's win against Cardiff after Hazard's hat-trick, who struck the decisive goal on seven minutes after good work by Barkley, who also came into the side.

The former Everton midfielder latched on to a Jorginho pass to burst forward from the centre circle and lay off to the left for Willian to sidefoot under the outstretched arm of goalkeeper Alexandros Paschalakis.

But while most of the Chelsea players were composed throughout, Morata endured a frustrating night after replacing Olivier Giroud up front.

Morata misfiring

Giroud linked up well with Hazard on Saturday and the way his replacement fared only strengthened the case for Sarri to make the Frenchman his first-choice centre forward.

Giroud is accustomed to squad rotation from his time at Arsenal, while Morata's form in front of goal fluctuated last season and he has only scored once in five starts this term.

Chelsea missed a number of chances to make the scoreline more emphatic and Morata was the biggest culprit. The Spain striker lacked sharpness, heading wide from a Pedro cross before dragging a left-footed shot wide from Antonio Rudiger's throughball.

And after being unable to keep a sidefoot volley down, Morata blazed over left-footed from the left side of the box.

Pedro should have doubled Chelsea's lead from a 38th-minute counter-attack, firing straight at the keeper after being picked out by Marcos Alonso, and from the resulting corner Morata steered a difficult header wide.

Willian twice went close to scoring his second goal after the break and Morata did well to find Alonso, who cut inside before seeing his shot deflected wide.

But after Paschalakis parried a Pedro strike, Morata cut a forlorn figure as he trudged off to be replaced by Giroud on 81 minutes.

Had he been more clinical, it would have denied PAOK the chance to mount a late rally, in which substitute Diego Biseswar fired straight at Kepa Arrizabalaga from the hosts' only effort on target.