The 21-year-old enforcer is widely regarded as on of Portugal’s top rising talents, and has already broken into his nation’s senior squad despite his youthful age.
His excellent fledgling displays have alerted a host of clubs, with Arsenal and United thought to be near the front of the queue.
Gunners chief Arsene Wenger is believed to have had scouts watch the rugged midfielder on multiple occasions, while United boss David Moyes has also bee keeping a close eye on his progress.
Sporting have a reputation for producing talented player, with Carvalho the latest to emerge from a youth set-up that has nurtured Cristiano Ronaldo and Nani.
The Lisbon giants are keen to keep their man, but with financial worries currently haunting them, a big money offer may be difficult to reject.
Carvalho has a whopping £37.5m release clause in his contract, but a figure significantly below that is likely to be greeted with a large level of interest at the Estadio Jose Alvalade.