Alexander Isak wants to explore his options for a move away from Newcastle this summer after missing the pre-season tour of Asia.
Newcastle have selected a 30-man squad but said the Sweden striker "misses out with a minor thigh injury".
It is understood that some of Europe's top clubs have been aware that Isak has been looking to take the next step in his career.
A source has told BBC Sport that Liverpool are still interested in signing the 25-year-old, despite signing Eintracht Frankfurt striker Hugo Ekitike for an initial £69m.
On Saturday Newcastle manager Eddie Howe said Isak would "absolutely" be part of the squad for the games in Singapore and South Korea.