The 18-year-old attacker plays in his homeland with Falkenbergs FF, who sit bottom of the Allsvenskan after claiming just nine points from 21 games.
Despite their woes, Karlsson has earned praise for his fledgling displays, he’s been capped at U-19 level by Sweden, and Man United and Sunderland are keen on him.
Fotball Direkt’s report centres around the Manchester outfit’s interest in the player, alleging contact has been made by the club regarding the starlet.
Sunderland are also reported to hold ‘concrete’ interest in Karlsson, who is thought to be available for between 6-8m Swedish Krona – which equates to between £500,000 and £700,000.
Should Man United wade in for the teenager, it’s likely Zlatan Ibrahimovic’s presence at Old Trafford may sway the forward, with ‘Ibra’ a Swedish national icon.
Karlssen made his senior debut at former club IF Boljan, aged just 14.