Youngsters Jock Cornell, Michael Luxford and Zac Bates have been omitted from Geelong's initial 29-man squad for Saturday afternoon's NAB Challenge game against Essendon in Shepparton.

But rookie-listed defender Tom Ruggles remains in the squad and will play his first official AFL game for the club.

The match will be played in stifling conditions, with a top temperature of 38 degrees expected.

As a result, the AFL's heat rule has been enacted, which means shorter quarters and longer breaks between them.

The Cats will wear black armbands as a mark of respect for 1989 Brownlow Medal winner Paul Couch, who has died at the age of 51.

ESSENDON V GEELONG
Deakin Reserve (Shepparton), 2.05pm AEDT, March 5 

Essendon
Out: Zach Merrett, David Zaharakis, James Gwilt

Geelong
Out: Jock Cornell, Michael Luxford, Zac Bates