MELBOURNE, Australia (AP) -- Top-seeded Novak Djokovic canceled a training session because of an undisclosed illness or injury on the eve of the Australian Open.

A spokesman for the International Tennis Federation, which handles media relations for the ATP Tour at Grand Slam tournaments, said Sunday that Djokovic ''was not well'' on Saturday and that he canceled the practice session at Melbourne Park and a pre-event press conference. The Serbian star scheduled another training session for Sunday afternoon.

Djokovic, a four-time winner of the Australian Open, is not scheduled to play his first-round match until Tuesday against Slovenian qualifier Aljaz Bedene of Slovenia.