The Swedish forward netted 29 goals in 53 appearances for the club, helping them secure the Carabao Cup and Europa League in 2017.
Now 22, Sesko is eager to follow in the footsteps of the ex-AC Milan star at Old Trafford.
"He’s been my role model since I’ve been small. I've been watching him, like every single YouTube video that I can find, because he's just amazing for me, you know," Sesko told Manchester United website.
"We don't have the same, let's say, character. But I like to see him, the way he plays, the way he enjoys football, because that's when all the joy comes, you know.
"If you enjoy football, then everything works. And I think this is the most important. It's probably also one of the parts that just makes me love him so much, you know what I mean? So maybe one day to meet him, that would be great. He's my idol."