Brentford are looking to strengthen the squad this summer.
According to Sky Sports...
Thomas Frank's side made an approach to sign the player on Wednesday, who the Reds value in excess of £20m.
The Bees are in search of a first-choice goalkeeper as Bayer Leverkusen close in on the signing of Mark Flekken.
The west London club are open to selling Flekken to the German club, who have just appointed Erik ten Hag as manager, and discussions are also underway to that end.