Rival clubs are reportedly monitoring Essendon key-position defender Brandon Zerk-Thatcher, as he remains without a contract heading into next season.

The 24-year-old has been a revelation in defence for the Bombers in recent seasons, frequently demonstrating his intercept-marking prowess and natural defensive instinct alongside reliable stopper Jordan Ridley.

Hence, interest in the 44-gamer isn't surprising, particularly considering his contract status.

According toย AFL.com.au's Riley Beveridge, the Bombers are understandably keen to retain Zerk-Thatcher, and clubs know that; however, due to his questionable contract situation, rival sides are understood to be keeping a close eye on the situation as the home and away season winds towards a close.

Zerk-Thatcher holds a non-free agent status this year, having served only six seasons in Bombers colours, meaning interested parties would have to strike a trade deal with Essendon in order to acquire the defender's services in 2023.

Adelaide's Tom Doedee, Geelong forward-turned-stopper Esava Ratugolea, and Roo Ben McKay represent the main crop of seemingly-gettable key defenders attracting the attention of rival clubs as the off-season trade and free agency period creeps closer.

This season's exchange period is set to take place in early October.