Frank Lampard’s men were hoping to build on their last weekend victory over Leeds United against the Toffees, but a Gylfi Sigurdsson penalty in the first half was enough to settle matters in Merseyside.
Chelsea lacked the guile and imagination to break the defense of Carlo Ancelotti’s men but managed to hit the post twice in each half.
Speaking to Sky Sports after the game, Lampard admitted it was tough to break Everton after their goal and was quick to defend Edouard Mendy, who conceded the penalty by impeding striker Dominic Calvert-Lewin.
"It was tough, it was a tough night for both teams, the difference was they got the early goal and stopped us playing after that,’ Lampard said.
"After that we found it too hard to break them down. We didn't play well."
"I don't know he got caught in the middle a little bit. He has been incredible since he has been here, I just think it was one of those,’ the former Derby County coach added when he was asked about the penalty incident.
"It was absolutely the game we expected and I expected. I expected the style of the game, the unity, the fans back in the ground.
"We are a young squad, new players that haven't won leagues. Sometimes you learn on your feet and tonight was one of those games.
"I am not going to criticize, when you have an off night you rely on other things like keep a clean sheet and then Mason's free kick goes in off the post, not the other way round."
Chelsea will look to atone for their sins when they entertain Wolverhampton Wanderers at Stamford Bridge on Tuesday.