Derby County goalkeeper Harvey Rees has made history by joining Baller League side Prime FC.The 18-year-old is the first active academy player to join the indoor football league.Derby Under-18s keeper Rees has joined Baller League side Prime FC on loanDerby CountyRees joined the Rams’ under-18 side as a scholar two years ago after a previous spell at Swansea City.The Welsh stopper is now set to make his Baller League bow on Monday night, though.Prior to night seven of season three, it was announced by the league that Rees had signed for KSI’s Prime FC on loan.The club are in action against Wembley Rangers AFC on Monday.Toby Bull has been the goalkeeper for Prime FC so far this season.The 22-year-old currently plays senior football for seventh-tier Dulwich Hamlet.As for Rees’ surprise arrival in Baller League, BBC Sport Derby report a medical waiver for the move has been signed.Rees goes to Baller League with Derby’s blessing, the report adds.The teenager was absent from the Rams squad for Friday’s Under-18 Premier League clash with Burnley.Bradley Johnson’s side played out a 2-2 draw at home to the Clarets at Pride Park.Derby have reportedly signed a medical waiver for Rees to play in Baller LeagueShutterstockView Tweet: https://t.co/P3Zkqbn8rHDerby currently sit 11th in the table with two matches of the season remaining.EFL stars in Baller LeaguePrime FC’s squad already includes former EFL striker Timmy Abraham, the brother of Aston Villa’s Tammy Abraham.A host of former professional players have featured in Baller League UK since it launched last year.Petr Cech even made a surprise appearance for John Terry’s 26ers back in January.However, the involvement of some non-league players has caused backlash from their clubs.Wealdstone released a statement last month after midfielder Sak Hassan appeared without permission from the club.KSI’s Prime FC face Wembley Rangers in Baller League UK on Monday nightAlamyMeanwhile, Dover Athletic terminated the contracts of two players after their involvement in Baller League.The National League South side confirmed that Francis Mampolo and Alfie Matthews had left the club days after featuring in the competition.