Man Utd have upped their interest in Benfica’s Joao Felix, after sending scouts to watch him in Portugal for fresh checks on the teenage sensation. The 19-year-old scored in a 4-1 win for his side over Santa Clara in Lisbon on Saturday, to help them seal the Primeira Liga title. As reported by the Star , United scouts were on hand to cast a watchful eye over Felix, who has attracted plenty of interest across Europe. Real Madrid , Barcelona and Man City are all said to been keen on the youngster, whilst Juventus have already had a £75m bid rejected. Representatives of Atletico Madrid were also in attendance at the fixture, as they look to replace the outgoing Antoine Griezmann. Benfica are resigned to losing their teenage prodigy, but will not accept less than £100 million. That is not thought to have put off United, with Ole Gunnar Solskjaer keen to invest in youth as he plans a summer rebuild of his squad. Felix has made waves in Europe this season, scoring 20 goals and making 11 assists in his debut campaign. The attacking midfielder has rose through the ranks at his current club, and could now be on…