The Old Trafford hierarchy has identified both players as potential additions, with Fernandes emerging as a leading midfield target and Summerville also attracting strong interest. Manchester United's recruitment team is understood to have stepped up its pursuit of Fernandes after exploring alternative options earlier in the window.
The Portugal Under-21 international is regarded as one of the most highly-rated young midfielders in Europe and has attracted attention from several elite clubs over the past year.
West Ham United are aware of the growing interest but remain determined to maximise any potential sale. The London club values Fernandes highly and would also demand a significant fee for Summerville, with the combined package believed to be worth as much as £140million.
That figure is likely to become a major point of negotiation.
While United remain interested in both players, there is little expectation that they would agree to West Ham's initial valuation without substantial discussions. Paris Saint-Germain have also monitored the situation surrounding the pair.
However, the French champions are balancing multiple transfer priorities and are not focused solely on Fernandes and Summerville at this stage of the window. United's interest in Fernandes appears particularly advanced.
The club has already held discussions around a possible deal and views the midfielder as a player capable of strengthening a department that could undergo significant change before the new season begins. Manuel Ugarte's future remains uncertain, while Casemiro continues to attract attention as United assess the shape of their squad moving forward.
Adding further midfield depth has become a key objective. The club has already invested in Atalanta midfielder Ederson and is expected to continue pursuing reinforcements before the market closes.
Fernandes fits the profile United have prioritised under Ruben Amorim. At 21, he combines technical quality with top-flight experience and has developed into one of West Ham's standout performers despite the club enduring a difficult campaign. Interest from elsewhere only reinforces his growing reputation.
Arsenal, Paris Saint-Germain and Real Madrid have all been linked with the midfielder, though United are believed to have positioned themselves strongly in the race. No formal offer has yet been submitted.
Personal terms are not expected to present a major obstacle should negotiations progress. Meanwhile, Summerville's stock has risen further following his performances on the international stage. The Netherlands winger delivered an eye-catching display in his country's World Cup opener against Japan and marked the occasion with a superb goal.
His contribution added to an encouraging first season at West Ham following his move from Leeds United. Summerville produced five Premier League goals and two assists despite the Hammers struggling for consistency throughout the campaign. The 24-year-old's pace, direct running and versatility have made him an attractive option for clubs seeking additional attacking depth.
Whether United pursue both players remains to be seen, but Fernandes and Summerville have firmly established themselves among the club's leading targets as another busy summer unfolds at Old Trafford.