The Fijian Drua have broken NSW Waratahs hearts with a pulsating and historic 39-36 Super Rugby Pacific win in tropical Lautoka.

Kemu Valetini snapped a field goal seven minutes into golden-point extra time to snatch victory after the Waratahs seemed poised to atone for two deflating two-point home defeats to the Highlanders and Blues.

The Tahs overcame extreme heat and a 16-point second-half deficit on Saturday to set up the grandstand finish in temperatures exceeding 30 degrees at Churchill Park.

The sapping conditions prompted officials to apply two water breaks in addition to the halftime break.

So when the Drua lost replacement halfback Peni Matawalu to the sin bin for a brain explosion at the ruck early in golden point, the Waratahs enjoyed a significant one-man advantage.

Alas, five-eighth Tane Edmed missed with a drop-goal attempt of his own before Valetini sealed a famous first-time victory for the Drua over the Waratahs.

"Like it's been the last two, three weeks, those sort of crucial parts of the game we let slip," said Waratahs captain Jake Gordon.

"We've just got to tighten up a few things. We we're in the fight, we defend well, but we need to find ways to win the game."

As evident by their round-two ambush of the defending champion Crusaders, Churchill Park - known as the Drua's "16th man" - is proving a fortress for visiting teams.

The Waratahs had made a flying start to lead 10-0 inside the opening 10 minutes.

Flanker Charlie Gamble put hooker Mahe Vailanu over in the fourth minute from a Waratahs lineout win before Edmed converted from the sideline and slotted a penalty goal shortly after.

But just as the Tahs threatened to pull off another runaway win over the Drua, like in their previous four encounters, the inspired home side produced a four-try blitz in the space of 20 minutes to seize control.

Olympic sevens gold medallist Iosefo Masi was at the centre of the fightback.

First he bamboozled World Cup trio Izaia Perese, Mark Nawaqanitawase and Max Jorgensen to score under the posts.

Then, either side of the softest of tries from Drua halfback Frank Lomani from a lineout, Masi collected his second and third five-pointers.

He out-paced the NSW defence for his second and snuck through a hole close to the line for his third as the Drua stormed to a 26-10 halftime lead.

Perese and centre partner Joey Walton combined well to put Gamble over shortly after the break to ignite the Waratahs comeback.

Tevita Ikanivere replied with the Drua's fifth try before Walton scored to again reduce the deficit to nine points.

With the hosts down to 14 men after replacement forward Kitione Salawa was yellow carded, the Tahs pulled to within a converted try when Vailanu bagged his second five-pointer.

It was all level at 36-36 when Lachie Swinton crashed over with 15 minutes remaining.

But Valetini's late intervention consigned Darren Coleman's side to their most crushing defeat yet this campaign of frustrating near misses.

Nawaqanitawase's milestone 50th game for the Tahs was a largely forgettable one.

Playing in front of his Fijian father's family, the classy winger spent 10 minutes in the sin bin for a deliberate knockdown to prevent a Drua try in the shadows of halftime and was offered few chances to showcase his silky attacking game.