The Red Devils confirmed the midfielders arrival earlier this week after a £52m deal was agreed with Shakhtar Donetsk, despite reports earlier this year strongly linking the 25-year-old with a move to the Etihad Stadium.
Pep Guardiola was said to be convinced by Fred's talent when City came up against the Ukrainian outfit in the Champions League late last year, so much so that within a fortnight the club opened talks over a potential deal.
Fred was seemingly on the cusp of becoming the most recent Brazilian to make the journey from Brazil to Ukraine and onto the Premier League in January, only for an injury to Vincent Kompany to curtail the deal.
According to Metro, Kompany's calf injury sustained against Newcastle late in December caused a change in priorities for Guardiola as he looked to Aymeric Laporte to fill the void at centre back in fear of watching his side's run at the title derail.
With City caught napping on the deal, Jose Mourinho and United pounced as they started negotiations with Shakhtar with little opposition, ensuring the Red Devils secured their man for £52m - the club's fourth most expensive player in history.
The 25-year-old is expected to add much needed dynamism to United's midfield brigade and offer Paul Pogba the freedom he requires to make an impact further up the field.
Fred sustained an injury whilst training with Brazil this week but it is not thought to be serious, ensuring his World Cup plans remain in tact where he will link up with his new club later this summer.