The NSW Waratahs have regained the Weary Dunlop Shield and dealt Melbourne's Super Rugby Pacific finals hopes a potentially fatal blow with a spirited 38-20 comeback win in Sydney.

While the Rebels were their own worst enemies, the Waratahs iced their chances to battle back from 14-0 down on Saturday night and take a giant stride towards the playoffs with a third straight victory.

The Tahs piled on 14 of their points while the Rebels were a player down, which added up to a quarter of the game at Allianz Stadium.

Skipper Brad Wilkin and lock Josh Canham were the culprits, both yellow-carded for cynically trying to pull down Waratahs mauls.

It wasn't only ill-discipline that proved costly for the Rebels, who looked the better side for much of the match.

The visitors butchered at least two try-scoring opportunities, winger Monty Ioane twice spilling the ball with the line beckoning.

Even in defeat, exciting young five-eighth Carter Gordon once again underlined his Rugby World Cup credentials in a dazzling display that must have impressed Wallabies coach Eddie Jones.

Gordon threatened to carve the Waratahs up almost single-handedly in an entertaining first half.

First he put Reece Hodge over with a delightful double-pump short ball then he showcased his brilliant running game to set up the Rebels' second try moments later to Ioane.

Gordon beat five defenders in a weaving 55-metre advance before the Rebels put the ball through the hands for Ioane to dot down in the left-hand corner.

The 22-year-old's two key injections had his side 14-0 up in as many minutes.

But the Waratahs swiftly struck back with their first penalty try after Wilkin's blatant intervention as the NSW maul attacked the Rebels line.

With the flanker off, the Tahs wasted no time cashing in on their one-man advantage, with captain Jake Gordon showing great foot speed to race 50 metres to score after pouncing on a loose ball from a lineout on halfway.

It was suddenly game back on at 14-14 before the Rebels snatched a three-point buffer just before the break through a Hodge penalty goal.

The Waratahs hit the front for the first time five minutes into the second half with their second penalty try following Canham's transgression - and were never again headed.

Carter Gordon showed he is not afraid of the rough stuff when he went toe to toe with Waratahs enforcer Jed Holloway in a heated push and shove, but it was the flyhalf's opposite number Ben Donaldson who had the last laugh.

Donaldson slotted four from four with the boot and put winger Dylan Pietsch over for the final try with a lovely flick pass at the death.

While the Waratahs leapfrogged the Queensland Reds back up into sixth spot with the bonus-point triumph, the Rebels remain second last, three points outside the top eight with three games remaining before the finals.

WARATAHS 38 (TRIES: Penalty Try 2, Gordon, Nawaqanitawase, Perese CONS: Donaldson 3/3 PENS: Donaldson 1/1)

REBELS 20 (TRIES: Hodge, Ioane CONS: Hodge 2/2 PENS: Hodge 2/2)

WARATAHS (1-15): Te Tera Faulkner, Dave Porecki, Harry Johnson-Holmes, Jed Holloway, Hugh Sinclair, Will Harris, Michael Hooper, Langi Gleeson, Jake Gordon (c), Ben Donaldson, Dylan Pietsch, Lalakai Foketi, Izaia Perese, Mark Nawaqanitawase, Max Jorgensen

RESERVES: Mahe Vailanu, Nephi Leatigaga, Archer Holz, Ola Tauelangi, Charlie Gamble, Teddy Wilson, Joey Walton, Harry Wilson

REBELS (1-15): Matt Gibbon, Jordan Uelese, Sam Talakai, Josh Canham, Trevor Hosea, Vaiolini Ekuasi, Brad Wilkin (c), Richard Hardwick, Ryan Louwrens, Carter Gordon, Monty Ioane, David Feliuai, Reece Hodge, Lachie Anderson, Andrew Kellaway

RESERVES: Alex Mafi, Cabous Eloff, Pone Fa'amausili, Tim Cardell, Tamati Ioane, James Tuttle, Stacey Ili, Joe Pincus

Referee: Damon Murphy

Assistant Referees: Jordan Way, David Conway