The 25-year-old midfielder shrugged off criticism of his form heading into Russia 2018 to help Les Bleus to global glory, with his tournament capped by a well-taken goal in the final.
Berbatov believes expectations will be met in 2018-19, with United looking stronger as a collective despite a lack of transfer activity.
The former Red Devils striker told betfair: “Jose Mourinho knows how to control to big players in the dressing room, to control egos, he's done it all his life and knows how to work it into the team.
“It's not easy for Mourinho, when teams are set up defensively against them because then it's when you need imagination, that Paul Pogba and Romelu Lukaku possess.
“Coming from experience as a former footballer, Pogba will start to see things getting easier for him now he has the confidence of winning the World Cup.
“On the pitch you can have the feeling that everything is happening for you, from passing to tackles. This should give him more momentum in the Premier League but he needs to stay strong.
“Sometimes self-esteem affects you on and off the pitch, until you face your next game and you miss an easy chance for example, then you feel not as great.
“However, he will be a world champion for life, now he needs to be a league winner. Top players at Old Trafford know how to be winners.
“He has all he needs, I don't think he needs to score the most to define his price tag, he has completely different things to do on the pitch and he's doing it his way. Brilliantly.
“Lukaku is scoring more goals and coming off his experience over the summer, he'll feel that he's a big part of Manchester United. He's intimidating in the box, very quick and has the players supplying him with the passes he needs.”
Mourinho will be under pressure to deliver success after ending last season empty-handed, with Berbatov confident that a first top-flight crown since Sir Alex Ferguson retired can be secured.
The Bulgarian added: “Manchester United need to get back to being champions again, to do this you need to do one thing, and one thing only, you need to win. It doesn't matter how many goals you score; one goal is enough if you don't let one in your net.
“It's getting more difficult as in the league, teams are getting stronger.
“Everybody wants to be the team that people say, ‘they play great football’, but at my time at the club and how we used to do things, there aren't that many changes. You still pass the ball and you move, it's not difficult, and now United have talented players in the team and can improve on being runners up.
“Mourinho is the best at this, you cannot question his ability with the silverware he's won. When I go back to the training ground, players tell me how the team is well built and I can't wait to see them as champions.”