The Portuguese club reportedly made a £3million offer for the 18-year-old which appears to have been accepted by the Scottish Premiership side.
Gauld is now set to undergo a medical with Sporting, although it has not been confirmed whether or not he has agreed personal terms.
Scotland U21 international Gauld was a first-team regular for United last season and was rewarded with a new deal in December.
His impressive displays earned him the nickname ‘Mini Messi’ and saw him linked with European giants Real Madrid and Roma, while Manchester United and Arsenal are also thought to have taken an interest in him.
But Sporting could have won the race to sign Gauld, who returned to Tannadice for pre-season training on Monday.
You'll be able to watch Sporting Lisbon in Champions League action next season on Sky Sports 5 - the new home of European football.
Considering this lad has a 60m Euro/48m pounds buyout clause already in his contract and Portuguese sides are generally good at spotting talent and then selling it for huge fees, I think he really could be rather good. I agree Sizemore, if it is true and Tom Ince had the chance to sign for Milan but has instead opted for Hull then there is partly the reason for England's woes in International competitions.- lfcfan80