Neymar joined Barcelona from Santos in the summer of 2015, and the attacker has scored 105 goals in 186 appearances for the Spanish giants - landing two La Liga titles, three Copas del Rey and one Champions League in the process.
The Brazilian international only signed a new long-term deal with Barcelona last October, meanwhile, and he is currently committed to the Spanish giants until the summer of 2021.
According to Sport, however, one of Neymar's trusted advisors has urged the 'frustrated' forward to leave Barcelona, telling the 25-year-old: "By the side of Messi you will always be second, you will always be in his shadow".
The same report claims that Neymar held discussions with Manchester United boss Jose Mourinho at the end of last season, and the Red Devils could launch a big-money move after hearing of the latest reports.
Manchester City, Real Madrid and Paris Saint-Germain are also said to be closely monitoring developments surrounding a player that has scored 52 times in 77 appearances for Brazil.