The settling of Alexander Isak's future "has to be right for Newcastle", manager Eddie Howe says.
The striker is considering his future at the club amid interest from Liverpool.
Isak did not travel with the squad to Singapore on Thursday, with Newcastle saying he had a thigh injury, but the Sweden international wants to look at a move.
A source has told BBC Sport that Liverpool are still interested in the 25-year-old, despite signing Eintracht Frankfurt striker Hugo Ekitike for an initial £69m.
Speaking before Sunday's pre-season friendly against Arsenal, Howe said: "Of course there's things going on behind the scenes.