The Melbourne Rebels have scored an historic 21-17 Super Rugby victory over the NSW Waratahs to jump into equal top spot in the Australian conference.

The Rebels humbled the Waratahs in front of 20,542 mostly-disappointed fans at Allianz Stadium to record their first-ever win in Sydney and join the Brumbies as surprise equal pool leaders.

The Waratahs’ sapping home defeat leaves the 2014 champions nine competition points adrift of their two big rivals ahead of a second bye next weekend and a massive conference derby with the Brumbies in Sydney in a fortnight.

The Rebels lost halfback and captain Nic Stirzaker midway through the first half to a head knock before resisting a late fightback from the Tahs to post one of the biggest wins in the franchise’s five-year history.

With a two-from-five start to their campaign, the Waratahs face an almighty battle to drag themselves back into finals contention under first-year head coach Daryl Gibson, who will also likely come under increasing pressure.

Tries to flanker Jack Dempsey and centre Matt Carraro gave the Waratahs a chance to snatch victory late, but it would have been an injustice.

The damage was done in a bumbling first half from the Tahs, when soft tries to five-eighth Jack Debreczeni and prop Toby Smith, plus a conversion and three penalty goals from Debreczeni earned the Rebels a 21-3 advantage at the break.

“Some of that stuff out there was rubbish,” Gibson fumed on Fox Sports during the interval.

“I want to see some pride in the jersey. Show the people of NSW what we can do.”

The pride, though, didn’t come from the Waratahs’ shaky set piece, with the Rebels drawing a scrum penalty in the opening minutes of the second half to immediately have the hosts under more pressure.

A try-saving tackle from Israel Folau – who earlier spent 10 minutes in the sin bin amid a mixed 27th birthday performance from the superstar fullback – on former NSW winger Cam Crawford kept the Waratahs in the contest.

But for the second game running, the Tahs’ second-half revival amounted to nothing and coach Gibson will be desperately hoping Kurtley Beale returns from an elbow injury for the Brumbies showdown.

His side’s attack looked utterly disjointed without their attacking linchpin.