The Brumbies defence couldn't answer all the questions posed by the Blues attack, slipping to a 39-34 loss in a Super 14 rugby thriller at Auckland's Eden Park on Friday.

The Blues scored five tries to three as 19 points from the boot of five-eighth Matt Giteau couldn't prevent the Brumbies suffering their first defeat in four games.

The Brumbies moved up to fourth with a bonus point, but only three points split the five teams immediately below them, all of whom have a game in hand on the Canberra-based franchise.

A four try blitz from the Blues in the third quarter proved decisive, as they marked the 100th Super appearance of captain and hooker Keven Mealamu in style.

Down 16-10 at the break, the Blues outscored the Brumbies 26-6 in 12 minutes early in the second half to carve out a 36-22 lead.

The Brumbies scored the next 12 points, with tries to replacements Huia Edmonds and Patrick Phibbs setting up a grandstand finish.

The visiting team couldn't manufacture another score after the 76th minute Phibbs five-pointer and Blues five-eighth Stephen Brett secured the points with a 79th minute field goal.

The Brumbies performed well in the set pieces and coach Andy Friend was pleased with the impact made by his bench players, but he lamented some costly errors and poor defence.

"We knew they were going to challenge our defensive line the whole night which they did and unfortunately we weren't able to sustain the reasonable effort in defence," Brumbies coach Andy Friend told AAP.

"We knew what was coming, that's the style of rugby they play ... they continued to ask questions of our defensive line and we didn't have the answers the whole time."

Friend said the full extent of a shoulder knock suffered by veteran flanker George Smith, who was forced from the field in the second half, probably wouldn't be known until Sunday.

The Brumbies host the Chiefs next week before having their bye and don't travel outside Australia again to the final round.

Sparked by centre Rene Ranger, the Blues always looked dangerous when they held possession and spread the ball.

Ranger and fellow centre Benson Stanley, winger Joe Rokocoko and fullback Isaia Toeva all crossed in the match-tilting period at the start of the second half.

The Brumbies held an early 10-3 lead highlighted by a try to prop Salesi Ma'afu.

The Blues levelled the score when Brett converted the first of Rokocoko's two tries.

Giteau kicked two penalties to give the Brumbies a 16-10 halftime buffer.

Ranger got the Blues within a point with a try inside two minutes of the second half and his bust set up the go-ahead try to Stanley.

Rokocoko caught a cross field kick from Brett and Toeava cut through some more ordinary defence as the Blues piled on two more tries.

Edmonds crashed through for the Brumbies second try just before the hour and Phibbs raised the Brumbies hopes further when he crossed following a great pass from flanker Rocky Elsom.

Brought to you by AAP © 2024 AAP