His start to life as a United player didn't get off to the best of starts though, after a nasty challenge from Real Madrid's Casemiro saw Fred miss days of Brazil training in the build up to the tournament in Russian Federation kicking off on Thursday.
However, when the 25-year-old limped out of training following a clash with Casemiro, the transfer was seemingly put into doubt.
Fred played no further part in the session and instantly received treatment.
Brazil's Manchester United-bound midfielder Fred injured his ankle in training on Thursday, a week before the start of the World Cup in Russia, British media reported. He also added that it was still too early to determine the extent of the injury. "If tomorrow he continues in pain and some signal makes us more alert, we may need an imaging examination".
"Today Fred had trauma in his ankle but it is too early to say anything about it". He sat out training on Friday - Brazil's last session in London before they fly to Vienna - to work alone with medical staff.
But Brazil manager Tite expects Fred to be fine to resume training with the national side ahead to the World Cup. Although United announced the deal on Tuesday, it's yet to be formally completed.
Brazil - led by head coach Tite - will face Switzerland (June 17), Costa Rica (June 22) and Serbia (June 27) in Group E at the World Cup in Russian Federation.