After facing rejection on their bids for Crystal Palace's captain Marc Guehi this summer, Newcastle are now looking towards signing a Danish player.
Mundo Deportivo says Newcastle are now switching sights to Christensen in frustration over Palace's stance.
Newcastle's last offer for Guehi was for £65m.
Christensen's contract with Barca runs until the summer of 2026 and it will take similar money to convince the Catalans to sell.