The Waratahs recovered from a poor first-half performance to beat the Rebels 31-26, their first win of the season.
Dave Dennis' troops served up a poor opening to the match, conceding a multitude of penalties and struggling with their execution in all areas. However, with the Rebels unable to take full advantage of their hosts' struggles initially, an improved second half showing was enough for the 'Tahs.
Brendan McKibbin opened the scoring via a third-minute penalty before James O'Connor levelled matters five minutes later. O'Connor put the Rebels ahead with a second penalty just before the end of the first quarter, but in between his two efforts were a multitude of mistakes from both sides.
Line-outs against the throw, re-starts straight into touch and a general sloppiness permeated the match, with the Waratahs the chief offenders in the early exchanges.
The Waratahs were made to pay for their ill-discipline when hooker Tatafu Polota-Nau was sin-binned in the 24th minute after referee Rohan Hoffmann had handed out a team warning minutes earlier.
The Rebels made the most of their numerical advantage soon after as hooker Ged Robinson dived over for the opening try.
The five-pointer came as the result of a well-worked move from a line-out, with Robinson going short to Cadeyrn Neville at the front of the line-out. The lock passed it out to Nick Phibbs darting down towards the touchline and with the extra man created, Phipps was able to put Robinson over.
McKibben and O'Connor traded penalties to see the Rebels take a 16-9 lead into the break, with the Waratahs sure to get an earful from coach Michael Cheika.
Whatever Cheika said initially seemed to have no effect as Drew Mitchell made a mess of the restart, but the Waratahs gradually began to find their feet.
It was the turn of Rebels prop Laurie Weeks to feel the wrath of referee Hoffmann seven minutes into the second period as he was sent to the bin after persistent infringements from the visitors.
The Waratahs looked set to make the most of the opportunity, with Mitchell and full-back Israel Folau both getting their side close before careless errors brought an end to the attacks.
Bernard Foley eventually got over the whitewash for the hosts in the 57th minute after a sustained period of pressure following a sniping break from McKibbin. The scrum-half converted to level matters at 16-16 and the 'Tahs never looked back.
Flanker Michael Hooper and replacement Paddy Ryan both got over for tries as the Rebels' charge faded under the new-found tempo created by their opponents.
Hooper was the beatifically of strong work from Ryan before the prop got his own name on the scoresheet after Mitchell had found space behind the Rebels defence.
Kurtley Beale dived over in the dying moments to ensure the Rebels walked away with a bonus point but it will be little consolation to the visitors after they fell away badly in a contest that was there for them to take.
For the Waratahs, a win represents progress, but Cheika will know that a repeat performance against the Brumbies next week is likely to herald a very different result.
Tries: Foley, Hooper, Ryan
Cons: McKibbin 2
Tries: Robinson, Beale
Cons: O'Connor 2
Pens: O'Connor 4
Yellow cards: Polota-Nau (Waratahs, 24th minute), Weeks (Rebels, 47th minute)
Waratahs: 15 Israel Folau, 14 Drew Mitchell, 13 Adam Ashley-Cooper, 12 Tom Carter, 11 Tom Kingston, 10 Bernard Foley, 9 Brendan McKibbin, 8 Wycliff Palu, 7 Dave Dennis (c), 6 Michael Hooper, 5 Kane Douglas, 4 Mitchell Chapman, 3 Sekope Kepu, 2 Tatafu Polota-Nau, 1 Benn Robinson.
Replacements: 16 John Ulugia, 17 Jeremy Tilse, 18 Paddy Ryan, 19 Greg Peterson, 20 Lopeti Timani, 21 Matt Lucas, 22 Ben Volavola.
Rebels: 15 James O'Connor (c), 14 Lachlan Mitchell, 13 Mitch Inman, 12 Rory Sidey, 11 Richard Kingi, 10 Kurtley Beale, 9 Nick Phipps, 8 Scott Higginbotham, 7 Scott Fuglistaller, 6 Luke Jones, 5 Cadeyrn Neville, 4 Hugh Pyle, 3 Laurie Weeks, 2 Ged Robinson, 1 Nic Henderson.
Replacements: 16 Shota Horie, 17 Paul Alo-Emile, 18 Jordy Reid, 19 Jarrod Saffy, 20 Nic Stirzaker, 21 Angus Roberts, 22 Tom English.
Referee: Rohan Hoffmann (Australia)