The Waratahs failed to avoid the ignominy of a winless Super Rugby AU campaign as they fell to a 36-25 loss to the Rebels.

A miserable 0-8 record was confirmed on Saturday as the Tahs were beaten by the Australian conference's second-bottom side, despite the Rebels having two men sent off in Sydney.

It took just 33 seconds for the hosts to get that sinking feeling as Stacey Ili touched down after collecting Matt Toomua's precise cross-field kick.

To their credit, the Tahs promptly hit back with a pair of Ben Donaldson penalties to suggest a close contest may be on the cards.

Even after Michael Wells' converted try restored some comfort for the Rebels, the dismissal of Isi Naisarani for a high tackle handed the home side fresh impetus.

Mark Nawaqanitawase and Jack Maddocks both dotted down to capitalise, with the Rebels clinging to a 21-18 half-time lead after a brace of Toomua three-pointers.

The visitors made light of their numerical disadvantage, Rob Leota diving over off the back of a maul, although Carlo Tizzano was quick to respond with a try of his own.

That proved to be the Tahs' last score, though, and the Rebels added gloss through Toomua's penalty and a late Matt Gibbon try.

There was still time for Pone Fa'amausili to see red for a driving his shoulder into the head of Max Douglas, but the 13 men saw out the remainder of the game without further incident.