Sage took over as Lens manager in June last year and led the club to a second-place finish in Ligue 1. In addition, Lens beat Nice to win the Coupe de France for the first time in their 120-year history.
It is understood Palace are keeping an open mind to their managerial search and want to take their time before deciding their new first-choice target.
Glasner, who led the club to the FA Cup last season and the Conference League this term, announced in January he would be leaving the club at the end of his contract this summer.
Coventry boss Frank Lampard, Ipswich manager Kieran McKenna, former Eintracht Frankfurt boss Dino Toppmoller, ex-Spurs boss Thomas Frank and former Burnley and Nottingham Forest manager Sean Dyche are also being considered with a number having already held talks.
Lampard has key admirers at Selhurst Park and is believed to be aware of Palace’s interest.
The former Chelsea midfielder and manager has enhanced his reputation at Coventry, leading the Sky Blues to the Championship title and Premier League promotion.
But Lampard currently has 12 months left on his deal and releasing him from Coventry is likely to cost a significant sum which could create a stumbling block.
Similarly, McKenna, who has led Ipswich back to the top-flight, is on big wages at Portman Road and is believed to have a release clause worth a minimum of £5m.
Frank, Toppmoller and Dyche are all without a club and would be more straightforward to appoint.
