Sky Sports is reporting that the Red Devils and the Blues, along with Everton, are all expressing an interest in signing the Brazilian attacker this summer.
According to the same report, Chelsea FC considered a move for Richarlison last summer before the 20-year-old ended up signing for Premier League rivals Watford.
The story also says that Watford are likely only to consider offers upwards of £40m for the Brazilian attacker in the forthcoming summer transfer window.
The attacker has made 36 appearances in all competitions for Watford this season and has earned praise for his strong displays.
He has scored five goals and made four assists in the Premier League so far this term.
Both Chelsea FC and Manchester United are likely to be keen to bolster their attacking options in the summer transfer window as both clubs look to try and assemble teams capable of winning the Premier League title next season.
Chelsea FC are currently down in fifth place in the table, while Manchester United are second and aiming to finish as runners-up to Manchester City.
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