Vieira had been set to begin training with United later this week, after a deal to acquire his services was agreed in principle with the Serie A club over a fortnight ago.
But Jokanovic instructed his employers to abort the arrangement after discovering the 23-year-old was unlikely to become available for selection until next month; by which time it would be too late to draft-in a replacement should further issues emerge.
Although the development is the latest in a series of blows the Serb has been dealt after taking charge of United earlier this summer, he felt he had no other choice but to send Vieira back to Genoa when details of his fitness record were revealed.
Questions will now be asked why Jokanovic and his staff were not made aware of these earlier in the process; long before Vieira entered quarantine in order to adhere to the UK’s Covid-19 protocols and their manager began drafting plans to incorporate the player into his starting eleven.
Jokanovic confirmed Vieira would not be completing the switch following United’s 4-0 defeat by West Bromwich Albion; a match Aaron Ramsdale missed after Arsenal agreed a price with their counterparts in South Yorkshire to recruit the goalkeeper.
United, who enter Saturday’s match against Huddersfield Town still searching for their first win of the new Championship campaign, had earmarked Vieira for the ‘pivot’ role in front of their defence, which would have enabled Oliver Norwood to take up a more attacking position and make better use of his creative qualities.
Vieira began his career at Elland Road, making more than 60 league appearances for United’s neighbours, before heading to Il Doria in 2018. Sampdoria are understood to have withdrawn him from their pre-season programme as early as mid-July, when Jokanovic’s employers first made contact. A dispute over who should pay the tax on the facility fee the Italians negotiated also delayed his arrival in England.