The 20-year-old midfielder, who is currently on loan from United with Granada, says the arrival of the Swedish superstar sent shockwaves through the Old Trafford dressing room.
"When he arrived, everyone could see that he was a real professional," he told Globo Esporte.
"Just by his physical appearance, you can tell he is professional as hell. He just wants to win – he only thinks about football.
"He brought his own physiotherapist with him, to treat him at the club. Everyone was left open-mouthed by that."