The Swedish striker is reportedly keen on a move to Anfield, but several hurdles remain before any potential transfer.
The forward has informed Newcastle of his desire to leave the Magpies this summer after Liverpool enquired about his availability.
Newcastle brace themselves for Isak bid
Newcastle's management will need to decide whether to sell their top scorer for the highest possible price or attempt to persuade him to stay at St. James' Park, as reported by Sportal.
Isak is not with his teammates in Singapore for pre-season, having complained of a thigh injury. Although medical examinations reportedly revealed no serious issue, the Swede remained at home.
Manager Eddie Howe confirmed the 25-year-old will not join the squad in South Korea either.
Liverpool is expected to receive £65 million from Bayern Munich for Luis Diaz and plans to use these funds to pursue Isak.
Newcastle values their star player at £150 million, a figure the Merseyside club is unlikely to match. Should a deal materialise, Newcastle will likely target Brentford's Yoane Wissa as a replacement.
RB Leipzig's Benjamin Šeško, Aston Villa's Ollie Watkins, and Chelsea's Nicolas Jackson are also reportedly on the Magpies' radar.