Denayer would be able to gain valuable Champions League experience should he join the Lions on loan.
The Istanbul giants were drawn against Benfica, Atletico Madrid and Kazakhstan side Astana in Group C of the competition.
French giants Marseille are also in the race to sign Denayer but would only be able to offer Europa League football.
Denayer has already held talks with Galatasaray and his agent Jesse De Pretter confirmed that his client could join the reigning Turkish league champions.
The agent claims that Galatasaray are among the two favourites to sign the young defender.
“Galatasaray are among the two clubs closest to signing Denayer we are going to make our decision over the next 24 hours,” Pretter told Fanatik.
The Istanbul giants won the league title for a record 20th time last season and are coached by Hamza Hamzaoğlu. The Lions have competed in the Champions league group stages for four consecutive seasons.