Haaland is widely expected to leave BVB ahead of the 2022-23 campaign, and a number of leading European clubs, including Barcelona, are likely to battle for his signature.
However, the Catalan outfit's financial problems could see them miss out on the Norwegian, and according to AS, Isak is viewed by the club as an alternative.
Last season, Isak found the back of the net on 17 occasions in Serie A, while he has netted twice in his last two appearances for Sweden, registering against Kosovo and Greece.
Real Sociedad are in a strong position when it comes to the forward's future, though, as he has a contract at the club until June 2026, with the deal said to include a release clause of €90m (£75.9m). body check tags ::