The Brumbies have gatecrashed the NSW Waratahs' homecoming to Allianz Stadium, edging their Super Rugby Pacific rivals in a 31-25 win.

In their first game at the venue in five years, the Waratahs were caught napping at key moments and Stephen Larkham's Brumbies will head back down the highway with a hard-earned victory.

There was some solace for the 25,076 fans present on Friday night, who got to witness the debut of highly-touted teenager Max Jorgensen.

The 18-year-old, who became the youngest Waratahs debutant since Kurtley Beale, grabbed two tries in a promising maiden outing at the top level.

A late penalty from Tane Edmed gave the home side a losing bonus point. 

Crafty Brumbies No.9 Ryan Lonergan was the star of the show for the visitors, grabbing 16 of his side's points - including the opening try - before being subbed off for Nic White in the second half.

Lonergan got his side in the lead when he backed up a pinballing run from Tom Wright, who was all too happy to exploit some sleepy Waratahs defence. 

The Tahs quickly found themselves back level when Jorgensen was able to support a rampaging Angus Bell and shrug off the tackles of Rob Valentini and Alan Alaalatoa to cross in the 15th minute.

Edmed added the conversion, but Bell's night was cruelled not long after due to a foot injury.

Lonergan and Edmed traded penalties before the hosts' fate took a twist just before halftime when they switched off at a Brumbies penalty.

Lonergan shaped to kick to touch on the near side before finding an unmarked Andy Muirhead on the other side of the field.

The winger skipped past Jorgensen to give his side a 15-10 lead going into the break.

Lonergan added two penalties after the Brumbies had a try chalked off for a foot in touch, with Jorgensen squeezing in at the corner to give the Waratahs hope of sealing a comeback.

Brumbies winger Corey Toole and NSW skipper Jake Gordon traded tries, but a missed conversion from Edmed allowed the visitors to maintain a buffer.

Noah Lolesio, who converted Toole's try, was able to add a further three points when Michael Hooper was penalised for not releasing at the breakdown.

Edmed was able to cut the deficit with a penalty goal in the dying stages to secure his side a losing bonus point.

Waratahs 25
Tries: Jorgensen 2, Gordon
Cons: Edmed 2
Pens: Edmed 2

Brumbies 31
Tries: R. Lonergan, Muirhead, Toole
Cons: R. Lonergan Lolesio
Pens: R. Lonergan 3, Lolesio

Waratahs: 15 Ben Donaldson, 14 Mark Nawaqanitawase, 13 Izaia Perese, 12 Lalakai Foketi, 11 Max Jorgensen, 10 Tane Edmed, 9 Jake Gordon (captain), 8 Charlie Gamble, 7 Michael Hooper, 6 Lachie Swinton, 5 Taleni Seu, 4 Jed Holloway, 3 Archer Holz, 2 Dave Porecki, 1 Angus Bell.
Replacements: 16 Mahe Vailanu, 17 Tom Lambert, 18 Te Tera Faulkner, 19 Hugh Sinclair, 20 Langi Gleeson, 21 Will Harris, 22 Harrison Goddard, 23 Nemani Nadolo.

Brumbies: 15 Tom Wright, 14 Andy Muirhead, 13 Len Ikitau, 12 Tamati Tua, 11 Corey Toole, 10 Jack Debreczeni, 9 Ryan Lonergan, 8 Pete Samu, 7 Rory Scott, 6 Rob Valetini, 5 Cadeyrn Neville, 4 Nick Frost, 3 Allan Alaalatoa (captain), 2 Connal McInerney, 1 Blake Schoupp.
Replacements: 16 Lachlan Lonergan, 17 James Slipper, 18 Rhys van Nek, 19 Darcy Swain, 20 Luke Reimer, 21 Nic White, 22 Noah Lolesio, 23 Ollie Sapsford.

Referee: Nic Berry
Assistant referees: Jordan Way, David Conway
TMO: James Leckie