The Waratahs won a minor premiership off the back of four-try bonus points but it was heroic defence that will see them play their first home final in Super Rugby history against the Crusaders at ANZ Stadium next week.

Tries to Alofa Alofa and Kurtley Beale and nine points from the boot of Bernard Foley built the Waratahs a 16-8 buffer by the 50th minute but 25 minutes of sheer bloody-mindedness on their try line kept the dream alive at Allianz Stadium on Saturday.

Determined not to disappoint the majority of the 38,800 fans who turned up for some Waratahs magic, Will Skelton put his back into it and sent Bernard Foley over the line to blow out the scoreline with four minutes to go.

But for most of the match last year's runners-up the Brumbies made the Waratahs' unbeaten run at home look like it might drop off a cliff. Only the home side's trademark but under-played defence and solid set piece set up a third grand final showdown with the Crusaders next week.

"We came up with a few - I won't call them lucky - but they were tries that we built under pressure," captain Michael Hooper told the post-match broadcast. "They're a tough team and a tough outfit, but we're in the final, I'm stoked."

The first half played out with a try apiece and one penalty goal extra to the home side separating the teams at the break. Alofa gave his team one heck of a parting gift with a 60-metre try in the third minute.

It was a classic intercept, Nic White's pass from the base of the ruck finding the NSW winger instead of White's man. Foley's conversion drifted wide to the left to leave the scoreboard 5-0.

Hooper continued his outstanding form this season, hanging off Jesse Mogg's shorts for three metres to defuse a Brumbies raid on the left wing. It wasn't the last the NSW captain saw of Mogg, making a crunching tackle on the rangy fullback that had the crowd on their feet.

Foley added three to the tally with a penalty in the 23rd minute. But the Waratahs soon gave their opposition an opportunity to attack when Phipps was penalised in the 27th minute. The Brumbies set up camp close to the Waratahs line and threw everything at it - lineout, scrum and Henry Speight.

The Fijian flyer took a floating pass from Toomua and had no one in his way to score his side's only try.

Christian Leali'ifano missed the conversion to leave the Brumbies trailing 8-5, but slotted a penalty with a minute to go to level the scores, just before Foley added his own to put NSW back in front 11-8 after the half-time buzzer.

The Brumbies went on the attack after the break and had their way at the ruck, leading to Leali'ifano's second penalty attempt two minutes into the second half. But the Test centre's once-laser accurate boot failed him for a second time and the Waratahs won a momentum-flipping scrum minutes later.

An Adam Ashley-Cooper grubber went into Mogg's mitts in the Waratah's 10m zone and the Brumbies fullback was too vulnerable. Beale stripped the ball and ran 30 metres to score in the 48th minute. Foley missed the conversion and Mogg was hooked in favour of Robbie Coleman. NSW led 16-8.

Speight put the visitors back with a trademark bust up the centre but pulled up injured soon after and left the field while NSW defended for dear life.

Test backs Joe Tomane and Pat McCabe were subbed on for the Brumbies along with Leon Power and Fotu Auelua, while the Waratahs injected crowd favourite Skelton for Kane Douglas into the second row.

What ensued will go down in Waratahs' folklore. Pinned on their try line the NSW pack produced its best-ever defensive effort to repel raid after raid from last year's runners-up. Foley's try was just reward for that effort. He converted to make it 26-8 and head into his first ever grand final.