Norwich City boss Daniel Farke says he is "angry and frustrated" with his sides performance at Championship newboys Millwall on Saturday.
The Canaries conceded three times in the first half, before Shaun Hutchinson's header finished off the 4-0 win for the Lions - their first in the campaign.
The Canaries have won only one of five games this season and conceded 12 goals after five games.
Defensive problems are continuing to be a problem for City, who, for a second weekend in a row, conceded four goals away from home.
Speaking to Norwich City TV, Farke said: "Our defensive behaviour in the first half was why we lost the game.
"I'm totally annoyed and frustrated about our defensive behaviour. I totally understand the fans' concerns.
"We have to improve. I'm hurt and the squad is hurt. We are angry and really sorry for the fans as that's not what we want to bring."
Meanwhile, it was a day also to forget for rivals Ipswich Town.
A record-breaking fifth straight win to start the league season proved too much for Ipswich, who lost 2-0 at Fulham.
Manager Mick McCarthy admitted his side were beaten by the better team, but praised goalkeeper Bart Bialkowski for a brilliant performance.
Peterborough moved to the top of League One after their winning start to the season continued with an impressive 4-1 victory at struggling rivals Northampton.
Gwion Edwards, Junior Morias, Jack Marriott and Marcus Maddison all scored for Posh, while another defeat for Northampton moves them to the other end of the table.
Saturday's other results
- Blackburn 4-1 MK Dons (League One)
- Gillingham 3-3 Southend United (League One)
- Barnet 0-1 Stevenage (League Two)
- Cambridge United 0-0 Morecambe (League Two)
- Colchester United 5-1 Forest Green Rovers (League Two)
- Mansfield Town 2-2 Luton Town (League Two)