The British and Irish Lions crashed to their first loss on tour in Australia Tuesday when they were upset 14-12 by the tenacious ACT Brumbies just days out from the opening Test against the Wallabies.

The Lions, fielding six injury reinforcements, were incohesive and nervous and were physically beaten at the breakdown by the Australian Super Rugby conference leaders, themselves missing six Wallabies in camp.

It was the Lions' first tour loss to a provincial side since going down 35-30 to Northern Transvaal in South Africa in 1997 and the first win by an Australian provincial team against them in 42 years since the Queensland Reds beat the tourists 15-11 in 1971.

Jake White's Brumbies were also the sixth Australian side, including the Wallabies, to keep the Lions try-less in a match.

"It's a massive result. This is a very young group of players who only got together 18 months ago and no one would ever have dreamt that we would have achieve Super Rugby-wise but to also get a win against the Lions doesn't happen," the former Springbok World Cup-winning coach said.

"The Brumbies even in their heyday couldn't do it so we're very mindful that this is as big as it gets for any boy who has played at this level."

The Brumbies scored the only try of the match in the fifth minute through impressive young centre Tevita Kuridrani, while fullback Jesse Mogg landed three penalties.

The Lions points came from two penalties each from Stuart Hogg and his second half replacement Owen Farrell.

"We felt that we didn't have the urgency and intensity that we needed in the first half, we were a bit better in the second, but obviously we're disappointed," Lions coach Warren Gatland said.

"It's part of being on tour. You regroup after you get a bit of a knock and you take your disappointment and it's how you respond to it, how this group of players respond to it this weekend. It's a reality check."

Match skipper Rory Best said the Lions were beaten in the physical battles and "smashed' in the breakdowns.

"We talked about not just about matching their physicality but beating their physicality and we didn't even match it," Best said.

"They really smashed us in the breakdown and they put a lot of pressure on us and our confidence started to go and many units just started to fall apart and we lacked some composure which again is very disappointing."

The Brumbies struck first when Fijian centre Kuridrani exposed some weak defence to score the opening try in the fifth minute.

Mogg initiated the chance with a long pass to Andrew Smith who linked with Kuridrani on the left-hand touchline.

Kuridrani easily beat the tackles from tour debutant Christian Wade and fullback Rob Kearney to score wide out.

The tourists resorted to high kicks from Hogg and Ben Youngs but they made little impression on the Brumbies, who looked the better side in the opening half.

The Brumbies missed three kicks at goal before Mogg landed a penalty for an 8-0 lead one minute from halftime.

The Lions faced going in scoreless at halftime for the first time since the 1980 tour of South Africa against Orange Free State (7-0) before Hogg kicked a penalty on the siren.

Welsh wing Shane Williams, who was summoned to Australia from Japan to help the injury depleted squad, almost scored with his first touch before he was bundled into touch and on another occasion he was in the clear but was called back for putting his foot in touch.

Mogg stretched the Brumbies' lead to 11-3 with a 45th-minute penalty as the Lions looked clueless in attack.

Scottish prop Ryan Grant conceded a penalty for twisting the head of Scott Sio and Mogg made them pay with his third penalty and a 11-point lead.

Hogg pulled three points back with his 57th-minute penalty, but he hit the upright with his next attempt to howls of delight from the home crowd.

Coach Warren Gatland sent on the replacements -- Geoff Parling, Richard Hibbard, Alex Corbisiero, Dan Cole, and Dan Lydiate -- to stir up the tourists and the introduction of fly-half Farrell got some much needed attacking rhythm.

Farrell kicked a penalty for the tourists to trail 14-9 with 16 minutes remaining, and the England number 10 pulled the tourists to within two points with another kick at goal with eight minutes left.

Toby Faletau was penalised for not releasing as the Lions went for the clinching try deep inside Brumbies' territory as the minutes ticked down.

But the Brumbies stoically held on to count down the clock to a famous win.