Former Manchester United manager David Moyes has told ESPN FC he is unsure whether Paul Pogba will develop into a player capable of having the kind of impact at Old Trafford that Eric Cantona and Ryan Giggs had on previous sides.

After joining United in a then world-record transfer deal Pogba failed to completely live up to expectations during his first campaign. But the signing of Nemanja Matic is expected to give Pogba the freedom to find his best form and help United challenge for the Premier League.

Although Moyes rates the France international he is unconvinced he is capable of making the difference in the big games.

When asked by ESPN FC TV if Pogba has what it takes to become a world-class player this campaign, Moyes said: "I think he's a top player, I don't know if he's a player who completely makes a difference for Manchester United. I think that over the years Manchester United have had players like Cantona, even Ryan Giggs, people who are special players. I don't know if Pogba's that.

"I think he's a good player, I think he'll add to Manchester United, but will he make the difference? Is he someone who will score the goal at really important stages in games or make the key pass? I'm not sure about that.

"But I do think that the machine that Manchester United are now, the size, the players they've got, you know they've got a massive stature to their team, I think Pogba adds to that. And I do think he's a good player, but I'm not quite sure if he'll make the difference in key games."

Paul Pogba and Romelu Lukaku are expected to be key men for Manchester United this season. Kevork Djansezian/Getty Images

Moyes also said United manager Jose Mourinho may have to change his playing style in order to get the best out of £75 million summer signing Romelu Lukaku.

"In the past the strikers Manchester United have had have not necessarily been of [Lukaku's] type," Moyes said. "I think there's been a different type of centre forward, strikers who link to play, strikers who were involved in the build-up.

"I don't know if Lukaku is there for that, I think Lukaku is there to get on the end of crosses and run in behind, which Manchester United will enjoy, they always like strikers who are willing to run in behind and I do think that Lukaku's record, his stature, you might see Manchester United playing a little bit differently.

"If you go back through history, Manchester United played with wingers, always had wide players, always crossed the ball in the box, and to be fair I think if Lukaku gets enough service I think he'll score enough goals."

Moyes managed Wayne Rooney at Everton and United, and has backed him for success following his return to Goodison Park this summer.

"I think it's a really good move for Everton," Moyes said. "I think even at the end of Wayne's time at Manchester United he was still scoring goals so the one thing Wayne is, he's a brilliant finisher, a natural finisher.

"He'll have to play differently now than he's done in the past, but I think it's a big thing for Everton as well. It shows that they're in business, they want to challenge the top teams and even if they get a good year out of Wayne, I think it's a good move to get Wayne back and I do think Wayne will score goals.

"I think it's the one thing he can do as well as anyone in the country as his goalscoring record proves, he's got as good a goalscoring record as anybody, if not better than everybody. So, I hope he does it for Everton and I think this year, I think it's a good move for Everton."