The Red Devils have suffered a poor start to the season - and are currently sat in 14th place in the Premier League - but Hargreaves, 44, thinks manager Amorim, 40, can turn the ship around if he lets the midfielder, 31, play in his more natural position of attacking midfield.
Speaking with TNT Sports, Hargreaves - who played at Old Trafford from 2007 to 2011 - said: “Defensively, I don't think they have [improved]. You look at Liverpool and Arsenal, you know who is going to play at the back.
“I think Ruben has rotated that back three so much that there isn't a settled partnership, and I think the quicker they can settle on a keeper and that back three and whoever plays in midfield [the better] because I think at the top of the pitch, with Bruno and [Matheus] Cunha and [Bryan] Mbeumo, they've got some good firepower.”
The former striker added Mbeumo, 26, could “release” Fernandes.
He explained: “He's not playing his natural position, he's playing deeper. He's playing as a box-to-box midfielder. Bruno's one of the best creators in the division. So you've got to play him in his natural position.
"But because they play two 10s, you could argue Man Utd's two best players last season were Amad [Diallo] and Bruno. They were the two 10s, and then they went and signed two more 10s in Cunha and Mbeumo when you didn't have a keeper or a striker.
“So they probably could have done that. But they decided to get goals and sign proven Premier League players in Cunha and Mbeumo, which I like. But now Bruno has to play deeper to get on the ball and create.
“So maybe he's not in the right defensive position because it's not his game, so that's on the manager to pick that. But I'd love to see Bruno play as a 10, maybe with Mbeumo as a No. 9. If you have Cunha and Bruno playing as two 10s plus Mbeumo, that's good.”
Reflecting on Amorim’s 3-4-3 formation, Hargreaves suggested the system wasn’t a lost cause yet, but insisted the players needed a reshuffle if the manager wanted the formation to be more effective.
He explained: “Ultimately, the manager is in charge. He picks how he wants them to play, and he wants to play that way. People act like it is a new formation.
“I won the Champions League playing like that in 2001 with Bayern [Munich]. A lot of it is personnel-dependent, so he's got a lot of his personnel, but Bruno Fernandes is probably not playing his natural position. He's playing deeper, and to say they struggle would be an understatement.
“I think everybody expected them to be a lot better this year with Cunha and Mbeumo, and they have been better, but the problem is you've still got issues at the top of the pitch with the striker. You've still got the goalkeeping situation, which is not clear.”
Manchester United are set to face Sunderland today (10.04.25) at 3pm UK time.
