Friday 15 September 2017 15:14, UK
Ronald Koeman admits feeling worried ahead of taking Everton to Old Trafford on Sunday after three straight defeats.
The Toffees have conceded eight goals in their last three games, without hitting the back of the net themselves.
A 2-0 loss at Chelsea, was followed by a 3-0 home defeat against Spurs, before Thursday's Europa League setback in Italy where the Merseysiders conceded three goals before half-time at Atalanta.
Next up is top-of-the-table Manchester United, a match that can be watched live on Sky Sports this Sunday. And Koeman says it is Everton's defensive frailties which are a particular concern.
The Dutchman said on Friday: "We have a lot of doubts. Last season we had a good defensive organisation. But we have lost our strengths - at the moment.
"If you lose that against the big teams in the Premier League, and yesterday too, it was painful because they showed more ambition, aggression, and defended so tight.
"And the space we gave to their [Atalanta] strikers was different. I don't tell the media what I tell the players.
"After this press conference, I will have a meeting with most of the players and the key players. I think it's time for the experienced players to stand up.
"Defensively there are too many mistakes. I am worried what I saw yesterday. I wasn't so worried after Chelsea. But it started second 45 minutes against Tottenham, and the first 45 minutes yesterday.
"We have some players with doubts, and I don't want to be too individual, because it's always a team performance, but we need to be more aggressive."
However, Koeman's recent record at United is good, picking up seven points from the last nine - as manager of Southampton and Everton.
And it would have been nine out of nine, had Zlatan Ibrahimovic not equalised with a last-gasp penalty in April.
He added: "The last three seasons I've had good results at Old Trafford but United are really strong - stronger than last season.
"And, at the moment, we are not at the level we were last season.
"But I have to believe we can come out of this. We know, with the Europa League, away games on Thursday night, then playing Chelsea and Manchester United on the Sunday [is tough].
"On a positive note, we only have one point less than last season but yesterday was a wake-up call."
