FANS have been encouraged to pre-purchase tickets to Sunday's NAB Challenge matches in Bendigo and Sydney, with both games almost sold out.

There are fewer than 500 tickets left for the clash between Collingwood and Carlton at Queen Elizabeth Oval in Bendigo.

Tickets are also selling quickly for Sunday's clash between the Sydney Swans and Fremantle at Drummoyne Oval, with fewer than 500 available.  

A limited number of club or AFL members may be able to scan into both venues, but the AFL is encouraging all fans to pre-purchase tickets to guarantee their entry on the day.