The 21-year-old moved to the Portuguese giants from the Red Devils during the recent summer transfer window, failing to earn a spot in Erik ten Hag's plans with the English side.
Fernandez has cemented a spot as the first-choice full-back for Benfica during his first few months at the club, scoring two goals and providing one assist across 11 Primeira Liga contests.
The youngster has also impressed on the continental stage, playing four matches in the revamped League Phase of the 2024-25 Champions League.
The Spaniard also possesses relative international pedigree, having represented Spain Under-21s on seven occasions since making his debut at that level in September 2023.
Benfica's Fernandez responds to Man United, Liverpool links
Speaking to Spanish outlet MARCA, Benfica man Fernandez has addressed rumours surrounding a potential switch back to the Premier League in the near future.
"I have people close to me and they are the ones who look at it more. To be honest, I do not pay much attention to it," stated the 21-year-old when asked about transfer rumours.
"I am focused on what I have to do because I have a game every three days. It is always nice to have teams call you and everyone wants to grow, but I am doing very well here. [Manchester] United have a signed purchase option, but I am very happy here.
"I have a five-year contract with Benfica. I want to win titles and continue to grow personally, as I am still only 21 years old. I want to win, whether it is with Spain or with Benfica, to continue to grow."
As alluded to by Fernandez, Man United possess a buy-back option in the deal for Fernandez, meaning that they have an advantage in the race for the left-back.
Man United's left-back issues
Near the end of his reign at the Theatre of Dreams, former Man United boss Ten Hag admitted that his side were keeping tabs on the progress of Fernandez at Benfica.
Although the Dutchman has departed and Ruben Amorim has taken charge, it is highly likely that the Red Devils will continue to monitor the young Spaniard.
Many pundits and supporters view Man United's decision to sell Fernandez over the summer as a mistake, especially considering his impressive form at Benfica to date.
The 20-time English champions have been left shockingly short of options at left-back so far this term, with Tyrell Malacia and Luke Shaw sidelined due to injury.