Dimitar Berbatov insists Ole Gunnar Solskjaer is only a part of the problem at Manchester United and the "attitude" of the players is a major cause for concern.
Pressure is mounting on Solskjaer after United suffered back-to-back defeats to Arsenal and Istanbul Basaksehir within the last week.
United have reportedly made contact Mauricio Pochettino and there is growing expectation the former Tottenham boss will take over at Old Trafford.
Pochettino has been out of work since he was sacked by Spurs in November last year but the Argentine remains highly rated.
But Berbatov has warned Pochettino's appointment may not turn things around at United, as there is a significant problem among the players.
"If there's truth to the Mauricio Pochettino rumours, it's hard to blame United really," the former Red Devils striker told Betfair . "When the team plays bad, the buck stops with the boss, and this has always been true.
"I saw him recently as a guest commentator, and he said he is ready to work again, so it's hard to stop those rumours. The one thing that won't change, however, are the players.
"A new boss won't change how they play. Yes, when you have a new manager you can see a bounce, but overall the attitude remains the same. No aggression, no passion, no holding each other to account.
"The players need to change their attitude as much as the manager needs to be changed.
"Many will say now is the time to make the change, others will say not yet, but watching this team now you probably would say there is something wrong."
United have just two wins from their opening six Premier League games this season and find themselves 15th in the table.
Do you share Dimitar Berbatov's concerns about the player attitudes at Manchester United ? Have your say here.
They travel to Everton in Saturday's lunchtime kick-off in what Berbatov believes to be a "must win" fixture for Solskjaer.
The Bulgarian added: "I've always been an admirer of Ole and a supporter of his, but if he continues like this then a change is inevitable.
"I still say United need a defender before they need a manager, a defender that is tactically aware.
" Everton on Saturday now is a huge game for United, and I think if they lose this, it's probably the point where they look for a new manager.
"They are 15th in the table, could be lower depending on other results if they lose Saturday, and that isn't acceptable for a club like United. It's must win for United and Ole Gunnar Solskjaer.
"The crazy thing is that tactically he is a fine manager. I saw his first 100 games record recently, and the numbers aren't that bad.
"However, it isn't the 1980s anymore. Managers don't get four years like Fergie did to win a trophy and improve the team, success must come quicker."
For more from Betfair Ambassador Dimitar Berbatov, head to www.betfair.com/berbatov
Sign up to the Mirror Football email here for the latest news and transfer gossip.
