Embalo, 16, is regarded as the brightest young prospect to emerge from the Benfica academy in recent years with United interested in bringing him to England while his star is still on the rise.
The Premier League giants dispatched Javier Ribalta, one of the club's most high-profile additions off the field during the summer, to watch over the teenage winger in a Uefa Youth League match against their United counterparts in October.
Subsequent reports in Portugal claimed a deal had already been struck between the two clubs for the Guinea-Bissau-born Portugal youth international, and while a meeting between United and Benfica did take place, his agent dismissed suggestions a deal was done.
Embalo's agent insisted clubs from England, Spain, Germany and France were tracking young client and Spanish daily Marca now reports Barcelona are one of them. They report the Catalan giants have been following his progress for "several seasons" with sporting director Robert Fernandez now paying particular attention to his rise in Portugal.
After missing out on another burgeoning talent in Vinicius Junior, who will join Real Madrid in 2019 after Los Blancos struck an astonishing £38m deal with Fluminnese in the summer, Barcelona have stepped up their interest in Embalo to avoid missing out on another young talent.
There will be no shortage of competition for his signature however with Marca noting both United's and RB Leipzig's interest – suggesting one of the clubs have already seen a €13m offer rejected.
They add Barcelona will take the season to decide whether they will follow up their interest with an official offer, which won't come until next summer.
Real Madrid have also been closely linked with Embalo in the past and it was rumoured back in May that they were willing to pay up to €15m (£13.3m, $17.4m) in order to beat a number of other high-profile European suitors to his signature.