The Gunners were hoping to sign Sima after keeping an eye on his impressive performances this season, but the Red Devils, who are also on the lookout for a right-winger, have put him on their radar as per MEN.
Sima has a long-term contract with Slavia Prague, which does not expire until 2024, and his transfer value as per Transfermarkt is around £10 million.
The 19-year old has put in some impressive displays for Slavia Prague this season and has already racked up some invaluable experience in the Europa League despite his age.
Sima has mustered up an incredible 19 goals and six assists in all competitions so far this season, so the interest from Manchester United and Arsenal does not come as a surprise.
Manchester United hoping Sima will be a future first-team star
Under the stewardship of Ole Gunnar Solskjaer, Manchester United have made a lot of progress and have managed to challenge Manchester City for the title.
However, there are still some areas on the pitch where they need to improve. The right-wing position is perhaps one of them, and instead of spending a lot of money on someone like Jadon Sancho, the club are looking to sign bright young players to fill the void.
Sima has done well for Slavia Prague's senior team since being promoted to the squad from the B team last summer. He has put in some thrilling performances this season already and has offered them a cutting edge in attack.
Manchester United have given several players opportunities to play in the right-wing position, but none of them have really impressed. In Amad Diallo and potentially Sima, they could have two talented players next season.
Although both are young, as long as they can keep performing in the first-team, as Marcus Rashford did some years ago, they could be the solution to the right-wing conundrum.
Manchester United’s interest will come as a blow to Arsenal, who will have considerably fewer funds this summer, and might struggle to attract players should they fail to secure European football for next season.