Fred has made just eight appearances for Brazil but is part of their 23-man squad for the 2018 World Cup in Russian Federation, and 2002 victor Rivaldo believes the midfielder will be the right fit for United.
Fred completed his medical at United's Carrington training ground on Monday after helping Brazil to a 2-0 victory over Croatia in their penultimate warm-up game at the weekend.
'But when you're a good player and a brilliant midfielder like he is, he's going to do well and he's going to be good for United'.
Mourinho's task will now be to harness Fred's passing ability, while also finally getting the best out of Pogba in his third season since an 89-million pound move from Juventus. "So I think Argentina and Portugal can do well".
The newspaper says United have agreed a deal worth around £52m including various performance-based add ons and Fred was all-set to be unveiled as their first major signing of the summer.
Fred has played 156 times for Shakhtar since joining them from Brazilian side Internacional in 2013, and has appeared in the UEFA Champions League regularly.
Fred's arrival has excited the Manchester United fans, with supporters pointing to his statistics in the Champions League as proof of his quality, while others said it is hard not to be excited about the player's arrival.
Even Ukraine's most capped player and former Bayern Munich player, Anatoliy Tymoshchuk, spent nine seasons with Shakhtar.