Timber missed the final weeks of Arsenal's 2025/26 Premier League title winning campaign - and the 2026 FIFA World Cup with the Netherlands - after a groin issue was flagged up to be more serous than first thought.
The call to send him back to the UK for tests is rumoured to be related to that injury, but there is no major concern over the former Ajax defender, as Mikel Arteta waits to see when he can return to match action.
His trip back is reportedly part of his wider recovery process and he could rejoin the squad next week if all goes well.
Arsenal kick off their preseason tour against LaLga side Girona on August 1st, followed by clashes with Real Betis, Borussia Dortmund and Como, before taking on old rivals Manchester City in the FA Community Shield on August 16th.