Graham Potter was left frustrated after his "second best" Chelsea side fell to a home defeat against Aston Villa at Stamford Bridge on Saturday.
Ollie Watkins gave Villa the lead with a deft lob after just 18 minutes, before John McGinn's first goal in 16 months put the game beyond Chelsea's reach in the second half.
The Blues lost despite accumulating 2.1 xG (expected goals) – their highest value without scoring this Premier League season – from 27 attempts, while Villa's goals came from their only two shots on target.
While Potter saw some positives from the display, he was left aggrieved by their failure to put the ball in the net and their sloppiness at the back.
"I think in both boxes we were second best," Potter told Sky Sports after the match. "The first goal for them is disappointing, we need to do a little bit better there.
"There are a lot of good things in the game. You look at the stats of the game and it's a positive performance, but in terms of the scoreline it's not because we're down in the game and we're all really disappointed.
"Ultimately you need to defend better than we did, and of course I'm responsible for that. We need to look at that and do better."
Potter does not feel his players' effort was the problem, with Chelsea having now lost and failed to score in four home games this season, their joint-most such defeats in a single Premier League campaign.
"The boys gave everything in the game," Potter insisted. "Their intention was there, the personality on the pitch was there.
"They tried. They had shots, they had attacks, they had entries into the box.
"If you look at the stats of the game there's a lot there for us, but ultimately the most important stat is the 2-0 defeat and we have to accept it and get better."
Chelsea will look to bounce back from another disappointing result when they host Liverpool at Stamford Bridge on Tuesday, looking to inflict a third straight league defeat on Jurgen Klopp's men.
Potter is thankful his side have an opportunity to quickly exorcise the demons from the Villa defeat, adding: "We can't feel sorry for ourselves. We have to respond.
"We're disappointed, everybody is. We have a fantastic game on Tuesday night to put it right."