The 18-year-old has recently burst onto the scene on Portuguese football with his pacey and technically adept approach drawing comparisons with Ballon d’Or holder Cristiano Ronaldo.
Such comparisons have led to suggestions that he will be the ‘next big thing’ in his nation’s game, and have alerted a host of clubs.
Reports claim that United and Arsenal are already looking at the teenager, as well as other teams from across Europe.
However, Benfica are reluctant to do business and will demand at least £40m for their starlet.
Famously, United and Arsenal both went in for Ronaldo when he left Sporting Lisbon in 2003.
Guedes has already represented his side 10 times in Primeira Division action, scoring once in the process.