Wallabies winger Drew Mitchell and fullback Kurtley Beale both scored a brace as the Waratahs handed the Rebels, the 15th team in the expanded southern hemisphere provincial championship, a lesson in finishing.
The Rebels had completely dominated possession in the first half but were unable to get any penetration and made to pay for their profligacy when the visitors finally shed their early nerves and hit their stride.
Beale finished off an expansive move in the corner on the Waratahs' first excursion into the Melbourne 22 after 25 minutes and six minutes later Berrick Barnes's kick for the corner was scooped up by Mitchell who made it 10-0.
Rebels hooker Ged Robinson was sin-binned after three minutes of the second half for trying to slow down Waratahs ball and by the time he returned, his team had conceded three more tries.
Hooker Tatafu Polota-Nau first wrestled over the line from close in, then livewire Waratahs scrumhalf Luke Burgess's inside pass put Mitchell over for his second with Beale matching his Wallaby team mate's tally five minutes later.
Centre Rob Horne made the most of a Waratahs overlap to bulldoze over for the sixth try with half an hour still to play and evergreen skipper Phil Waugh emerged from a try line pile-up to claim the seventh.
"It was a big game for Australian rugby and a big game for Melbourne," Waugh said in a pitchside interview. "They threw everything at us in the first 15 minutes but we came out and played some good football in the second half."
Former England flyhalf Danny Cipriani, who came on from the bench to replace the injured James Hilgendorf after nine minutes, missed the Rebels' one kick at goal.
Barnes started as errantly by missing the first three conversions but found his touch later to slot over his last three attempts, Beale adding the last two-pointer.
"We didn't nullify their threats enough," Rebels skipper Stirling Mortlock said. "Their back three are class. But to have 25 000 Melburnians come out tonight was amazing."
Teams
Rebels:
15 Julian Huxley, 14 Lachlan Mitchell, 13 Stirling Mortlock (captain), 12
Cooper Vuna, 11 Luke Rooney, 10 James Hilgendorf, 9 Sam Cordingley, 8 Gareth
Delve, 7 Michael Lipman, 6 Hoani Macdonald, 5 Kevin O’Neill, 4 Adam Byrnes, 3
Greg Somerville, 2 Ged Robinson, 1 Nic Henderson
Substitutes: 16 Heath Tessmann, 17 Laurie Weeks, 18 Alister Campbell, 19 Jarrod
Saffy, 20 Nick Phipps, 21 Danny Cipriani, 22 Afusipa Taumoepeau
Waratahs:
15 Kurtley Beale, 14 Lachie Turner, 13 Rob Horne, 12 Tom Carter, 11 Drew
Mitchell , 10 Berrick Barnes, 9 Luke Burgess, 8 Ben Mowen, 7 Phil Waugh
(captain), 6 Dave Dennis, 5 Kane Douglas, 4 Dean Mumm, 3 Al Baxter, 2 Tatafu
Polota-Nau, 1 Sekope Kepu
Substitutes: 16 Damien Fitzpatrick, 17 Benn Robinson, 18 Sitaleki Timani, 19
Chris Alcock, 20 Brendan McKibbin, 21 Daniel Halangahu , 22 Ryan Cross