Dynamic Sydney youngster Isaac Heeney is likely to miss the start of the Swans’ AFL campaign after being diagnosed with glandular fever.

Heeney missed last Friday’s pre-season match against GWS Giants with a virus, which the club has now confirmed as glandular fever.

“Clearly this is disappointing news for us and for Isaac as he has had a terrific pre-season to date,” Swans’ head of football Tom Harley said on Tuesday.