United paid about £89.3m to bring Pogba back from Juventus in August, and though he's played consistently for Jose Mourinho, the 23-year-old has come into criticism since a underwhelming display in the EFL Cup final last month.

Pogba has scored just four times in 25 appearance in the Premier League this season, and Lampard said United should be expecting a bigger return on their investment.

"It was a signal of their intentions to spend £90m on player who I wouldn't say is the finished article," the former Chelsea star said on Sky Sports on Monday. "He's got fantastic attributes. He's strong, he's got great feet, he's bigger than you and he's quicker than you as a midfield player.

"But when you have a £90m price-tag on your shoulders, we analyse more and we want more. I'm still wondering, what's his best position? What kind of player is he? What does he want to be?

"I feel a little bit like he has fallen in between everything. When you pay £90m you want to see results, and he hasn't quite delivered. He's young and he possibly will do, but as it stands he hasn't been a game-changer."

Man United fans need to give Paul Pogba a little more time to live up to expectations, Frank Lampard says.

Lampard conceded that the high transfer fee may have raised expectations a little too high for a player who has never scored more than 10 goals in a season.

"The problem he has is all of our perceptions," Lampard continued. "Who would you pay £90m or £100m for? [Luis] Suarez, [Cristiano] Ronaldo, [Lionel] Messi.

"They bring 40 to 50 goals a season. They win games on their own week in, week out. We don't know that Paul Pogba can do that yet, but he's being judged on it.

"We need to give him time. We need to flip forward to next season and see if he's improving his game. But at some stage he has to be that dominant midfield player because I do believe that's in him.

"The problem for me is that if you spend £90m, you don't want a £90m problem."