Sunderland boss Sam Allardyce says he is concerned by his team's defensive frailties after losing 6-2 at Everton.
The Black Cats achieved a first clean sheet of the season against Newcastle last Sunday but, having got back to 2-2 at Goodison Park, they then conceded three goals in seven minutes.
"The defensive frailties were just too much in the side," Allardyce said.
"If we don't sort those out and give it away like we did at 2-2, then it'll be a long haul over the next few months."
Sunderland hit the post twice before Everton took a two-goal lead. The visitors clawed back to 2-2 through Jermain Defoe and Steven Fletcher after 50 minutes, but just 12 minutes later they were 5-2 down.
Aroune Kone added a late header to complete his first Everton hat-trick as Sunderland remained second from bottom in the Premier League, two points from safety.
Allardyce, who has never been relegated and has seen his side lose two of his three games in charge since taking over on 9 October, added: "We had 17 attempts on goal and 12 on target.
"At the top end we can score a goal and create chances but until we get into the habit of defending better out of possession it is worthless how many goals we score if we defend like that.
"That lack of discipline and organisation as a team is obviously the biggest concern for me."
Sunderland got 'carried way'
The former West Ham, Newcastle and Bolton boss picked a 3-5-2 formation for the game at Everton, but wing-backs Patrick van Aanholt and DeAndre Yedlin were often caught out upfield.
Allardyce defended his tactics, saying: "I gave them more protection today to look after themselves defensively, but when we got back to 2-2 we decided not to do that side of it and we were going for a third goal.
"If you go an try and win then you play right into Everton's hands. I need the players to understand what an opportunity they had today to at least get a result.
"They let their emotions get carried away. If you allow them spaces by going AWOL, then they will exploit those spaces and that's why they scored six and why we scored two."