Manchester United have completed the signing of Karim Cassim from Manchester City.The 17-year-old midfielder has joined the Red Devils after his move was ratified by the Premier League.Cassim has joined United from City after his transfer was ratified by the Premier LeagueGettyCassim was part of the City side which won last season’s FA Youth Cup, beating United in the final back in May.Although the teenager was an unused substitute in that match, he scored three goals in 10 Under-18 Premier League outings last term.United are understood to see Cassim as a future first-team player following his arrival at Old Trafford.The youngster has won three caps for England at Under-17 level, with each of those coming in March of this year.He will now join up with the club’s Under-18 squad, which includes wantaway wonderkid JJ Gabriel and Kai Rooney, son of United legend Wayne.Cassim could make his debut for the side against Chelsea in the Under-18 Premier League Cup on October 10.As well as their FA Youth Cup triumph, he won the Under-18 Premier League North with City last term.However, they were ultimately beaten in the national final by Chelsea.United eye further dealsAccording to The Athletic, Cassim will not be the last promising youngster to join United with more deals planned for the near future.The Red Devils are also working to confirm the signings of David Eze and Isaac Konde from City and Liverpool, respectively.View Tweet: https://x.com/ManUtd/status/2103048208561648071?ref_src=twsrc%5EtfwGerman winger Noah Ajayi is also set to be handed his first professional contract, the report adds.The 17-year-old joined United’s academy back in 2019 after starting his youth career with local side TSV Sasel in Hamburg.Meanwhile, Eze would be following in Cassim’s footsteps by arriving from City.The midfielder, 16, is part of the latest England Under-17 squad chosen for the current international break.He could feature against Israel, Venezuela and Germany in a four-team tournament next week.As for Konde, his arrival would follow a departure from Liverpool.Cassim won the FA Youth Cup with City last season and has three caps for England’s Under-17sGettyThe midfielder turns 17 next month, but unlike Eze and Cassim has yet to represent the Young Lions.Konde made six appearances for the Reds in the Under-18 Premier League last season, providing one assist.