Former Sporting CP manager Carlos Carvalhal has hailed Bruno Fernandes as a player from "another planet".
Manchester United completed the signing of the Portugal international for an initial fee of £46.5m on Thursday.
And Carvalhal, who has links with Sporting having managed the club in 2009/10, believes United have pulled off a fantastic deal.
"He is really very good,” the former Sheffield Wednesday and Swansea head coach told talkSPORT.
“He is a player from another planet, the planet of Portugal is very small to him in this moment, he’s an extraordinary player.
“Bruno is the best player in the league, he’s miles ahead of the others.
“He is a complete player, and if you ask me to compare Bruno with a player, I will say Frank Lampard.
“Last season was fantastic, he scored 20 league goals, the season before he scored 11 and this season he has eight goals and seven assists, and this is a midfielder, not a winger or an attacker.
“He has very good deliveries in free-kicks, makes very good assists, he’s an athlete. He’s not a number 10, he’s an eight in my opinion, he’s a worker, a box-to-box player.
“He also reminds me of Joao Moutinho, who I had at Sporting. I think Bruno Fernandes is different, because he has more goals, but they have something in common – they understand the game very well. He is very organised, he is always talking.
“Bruno Fernandes is another level to Joao Felix in my opinion, but I don’t know if Bruno at 19 years old was the same level as Felix is now.
“He is 25 years old, he is in the Portugal first XI and he would be a fantastic addition in my opinion.”
Fernandes could make his United debut when Ole Gunnar Solskjaer's side face Wolves on Saturday.
The Red Devils are currently six points adrift of fourth place, which is currently occupied by Lampard's Chelsea.
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