Golden Slipper hopeful Invader has become the second horse in doubt for the $3.5 million race after being found to have a stone bruise.

The Peter and Paul Snowden-trained colt will be monitored throughout Friday, the eve of the big race.

Peter Snowden told stewards Invader was displaying tenderness in his off-fore foot and was being attended to by the stable veterinarian.

Racing NSW chief veterinary officer Craig Suann will inspect Invader on Friday afternoon.

Suann will also re-examine the Gary Portelli-trained Single Bullet who suffered abrasions to his forelegs when he became cast in his box.

Single Bullet passed an inspection on Thursday with another examination scheduled, also for Friday afternoon.

Invader is a well backed $18 chance with Sportsbet in Golden Slipper markets.