The Waratahs edged the Rebels in a high scoring thriller in Sydney to keep themselves in playoff contention.
The playoffs are not entirely in their hands as they need to pray for a miracle next week while on their bye, the Western Force beat the Rebels, or at the very least deny them a bonus-point win.
The Rebels opened the scoring with a penalty in the 3rd minute, but it was the Waratahs who got off to the better start as they scored two converted tries in the first 20 minutes either side of To'omua's missed penalty attempt.
Rebels didn't panic as they hit back following a yellow card to Hanigan. To'omua crashing over before adding the conversion.
Waratahs got a late penalty on the hooter to take a seven-point lead into half time.
Rebels came out firing at the start of the second half as Naisarani crashed over before To'omua kicked the conversion to tie things up.
Walton scored his first Super Rugby try before Koroibete scored in the corner
Naisarani scored his scored, but To'omua missed the conversion. That made it a two-point game.
Harrison scored off a Rebels mistake to take the lead to 9 points and seal the win.
With 4 miuntes to play, To'omua slotted an important penalty to take a earn a losing bonus-point that leaves the playoffs in their hands next week.
Waratahs will spend their bye week, full of nerves as they hope the Western Force do them a favor next week.
Top Players of the Day
Isi Naisarani - Two crucial tries, was a menace with ball in hand and was all over the field.
Jack Dempsey - Was a constant threat from the back of the scrum. Fantastic at the breakdown and deserved his try
Matt To'omua - Kept Rebels in the game with accurate kicking out of hand, solid defense and managed the game well.
Jake Gordan - Brilliant support play, kept the Waratahs on the front foot and gave them good front foot ball.