According to joint reports from L'Équipe and RMC Sport, there is now no doubt about the French coach's future.
Since a definitive split at the start of last week between the coach and RC Lens, talks have accelerated with Crystal Palace. A comprehensive agreement is now very close to being finalised between all parties.
Voted best Ligue 1 coach at the UNFP Awards after winning the Coupe de France and finishing second in the league behind PSG, Sage had already reached a personal agreement with the Eagles.
In London, a contract until 2029 (with an optional extra year) awaits him.
Although Sage still had two years left on his contract in France, his departure is not a loss for the club.
According to RMC Sport and L'Équipe, Lens and Crystal Palace have agreed on a fee of 3 million euros to be paid by Palace, as well as 2 million euros in bonuses (£4.32 million total).
This now-confirmed departure will allow the Lens management to officially begin the search for his successor.
Again according to L'Équipe, RC Lens is preparing to finalise the arrival of its new coach, with Olivier Pantaloni emerging as the leading candidate.