In December 2020, United held talks to sign then-19-year-old Caicedo from Ecuadorian side Independiente del Valle only to eventually back out of the move.
Reports at the time suggested the involvement in third party intermediaries compromised their interest, with Brighton going onto sign him for just £4.5million in January 2021.
Caicedo would develop into one of the best young midfielders in the Premier League, joining Chelsea for a British-record fee of £115million last summer.
United were left to rue a missed opportunity but are now monitoring another young talent in Zambrano, currently playing for LDU Quito in the Ecuadorian top flight.
Luton Town have been monitoring the 19-year-old for a number of months, according to El Futbolero.
But the publication now reports United and Brighton are also interested in bringing him to England during the January transfer window.
Luton have reportedly already made an offer to sign Zambrano but his club have decided to wait for other bids given the emerging interest from United and Brighton.
The report adds United regard Zambrano as ‘the new Caicedo’, believing he has shown similar characteristics to the current Chelsea star, and are wary of missing out on another prized talent from South America.
United are not expected to be busy in the January transfer market with major additions to the squad unlikely.
The Red Devils are keen to bring in another striker to ease the pressure on Rasmus Hojlund and have reportedly enquired into the availability of former Chelsea forward Timo Werner, now of RB Leipzig.
Bayern Munich’s Eric Maxim Choupo-Moting is also on their shortlist of targets, along with his teammate Thomas Muller.
United are also interested in Stuttgart striker Serhou Guirassy, who has a release clause of just £15million.
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