Man United moved quickly to beat Newcastle to long-term target Sesko, 22, signing the striker from RB Leipzig for a reported fee of £74 million.
Amorim has already added Matheus Cunha and Bryan Mbeumo to his squad as they have successfully overhauled a stagnant attacking line-up.
Speaking to the press after their friendly with Fiorentina, Amorim was full of praise for his latest signing.
He said: "He has the characteristics that we needed. He's a player that, with all the information we have, we need to stop the guy from working. It's not the opposite, that is also important.
"He's really young. He's good in the air. He's good running the channels. He's good on the ball. So I think he has great potential. I think he can improve a lot, and for sure he's going to feel at home in our club. He's the right character to be in this group. So we are really, really happy to have him."