Well, the Catalan giants are said to be looking for a long-term replacement for Andres Iniesta with the 32-year-old getting no younger, and they are said to have been impressed with the performances of Herrera this season.
Barca believe that the Spaniard would fit in well to their style of play having featured for Athletic Bilbao in La Liga before.
However, he isn’t their only target and Liverpool’s Philippe Coutinho and Paris Saint-Germain’s Marco Verratti are also said to be on their radar.
The 27-year-old has become a key man in midfield for the Red Devils and he has scored one goal and provided a further six assists in 27 Premier League appearances.
He showed his importance to the side when he scored one and assisted the other in the 2-0 win against leaders Chelsea at Old Trafford earlier this month.
The Portuguese boss will want to strengthen his squad rather than losing key players this summer and with Michael Carrick getting no younger and Marouane Fellaini unlikely to be a regular next season, it is vital that he keeps the impressive Herrera at Old Trafford.
If the midfielder wanted to return to Spain or play for Barcelona then the situation could change as United won’t want to keep a player that doesn’t want to be at the club.
Having become a key man in the Manchester United midfield it seems unlikely that Mourinho would be willing to sell Herrera or that the Spaniard would want to leave, but the lure of playing for Barcelona could be too good to turn down.