According to reports, United are expected to lodge an initial offer later this week, but the proposal is likely to fall well short of West Ham's 80 million-pound asking price.
The 21-year-old has emerged as one of the most sought-after young midfielders in Europe after an impressive campaign despite the Hammers' relegation to the Championship.
Fernandes is understood to favour a move to Old Trafford above all other options. United are confident that agreeing personal terms would not be a major issue, with the player eager to compete in the Champions League following Michael Carrick's successful first full season in charge.
Carrick earned widespread praise after guiding United to a third-place Premier League finish and is keen to add quality to his squad ahead of a return to European competition.
However, the United manager may need to be creative in his approach. While Fernandes is regarded as a player with enormous upside, club officials are reluctant to meet West Ham's full valuation given his relatively limited experience at the highest level.
West Ham are reportedly trying to generate interest from multiple suitors, with Arsenal, the reigning Premier League champions, as well as Champions League holders Paris Saint-Germain and Spanish giants Real Madrid all monitoring the situation.
Although the club would prefer to keep Fernandes, Financial Fair Play considerations could eventually force them to listen to offers.
The midfielder joined West Ham from Southampton for 38 million pounds in the summer of 2025 after leaving the Saints following their relegation. Southampton also negotiated a 15 per cent sell-on clause and would benefit from any future transfer.