The Rebels fell to a dramatic 38-32 defeat to the Waratahs but Matt Toomua's late penalty significantly enhanced their Super Rugby AU finals hopes.

Toomua split the posts from an acute angle in the 77th minute to secure a losing bonus point, meaning the Rebels will reach the knockout stage at the expense of the Waratahs if they overcome winless Western Force by four points or more next weekend.

Jake Gordon put the Waratahs – who, with a bye in the final round, needed a bonus-point win and to deny the Rebels one to seal third place – ahead and they had a 17-10 lead at half-time, with Toomua converting his own try to reduce the deficit after Jack Dempsey went over.

Harry Johnson-Holmes' score and Australia captain Michael Hooper teeing up Joey Walton put the Waratahs in control after a frantic start to the second half.

Marika Koroibete and Isi Naisarani touched down as the Rebels began to fight back – the latter going over for the second time in the game while Matt Philip was in the sin bin for repeated infringements.

The Waratahs moved nine points clear, though, when Will Harrison forced his way over in the 74th minute and then added the extras after Andrew Deegan's kick was charged down by Hooper.

However, Toomua's late penalty ensured the Rebels did not leave empty handed and have their future in their own hands with one game remaining.