Adam Ashley-Cooper keeps the intensity up during a Waratahs training session.

Adam Ashley-Cooper keeps the intensity up during a Waratahs training session. Photo: Getty Images

NSW Waratahs back Adam Ashley-Cooper says a win over Super Rugby Australian conference leaders the Brumbies on Saturday is vital, as he prepares to make an emotional return to Canberra.

The Waratahs are five points behind the Brumbies following a 37-33 home loss to the Crusaders in Sydney yesterday.

A loss to the Brumbies could leave them nine to 10 points behind, with just half a dozen games to go.

''It is a crucial time in the competition for us, a win next week is vital,'' Ashley-Cooper said yesterday.

''If they get a win they skip further ahead, if we win we get closer to claiming that number one in the Australian conference.''

After playing seven years and 78 Super games for the Brumbies, next Saturday marks Ashley-Cooper's first game against his former team.

''I'm actually looking really forward to it, I'm not going to take too much distraction away from the team performance, but personally I'm looking forward to getting back there and getting a win,'' Ashley-Cooper said.

''I love playing down there. Obviously there's going to be a lot of emotion going back down there and playing.''

He was impressed with the Brumbies' ability to win the ball at the breakdown and the skills of their backs.

The loss to the Crusaders was the Waratahs' fifth of the year and their fourth by four points or fewer.

''It's no good being close enough, at the end of the day you want to win, you want to get those points,'' he said.

''We're yet to close out games, grind out games, particularly in that 50 to 60 minute mark.

''A little bit of ill discipline, a little bit of technical errors are letting us down at critical moments.''

He lined up at fullback but said there was connection missing in the back line, as some of them attacked and defended in different positions.

The lethal speed of Robbie Fruean brought the Waratahs' mid-season momentum screeching to a halt as the Crusaders continued to climb up the ladder.

The Wellington-born centre scored a double for his highly fancied team in an explosive partnership with winger Zac Guildford that blew holes in the Tahs defence to give the visitors a bonus point.

It was a classic third-quarter drift from the home side, which went into the break one point behind its opponents having dominated at the lineout, contested valiantly and jagged the lion's share of turnovers but failed to convert opportunities.

''We gave them possession at key times,'' coach Michael Foley said.

''Obviously on the restart a couple of times there we spilled the ball, but again it's difficult to be critical because they just contested very hard.''

Strongman No.8 Wycliff Palu fuelled hopes of an upset with a beautifully opportunistic try off a rolling maul early in the second half but the Crusaders attack fired up again to put a win just out of reach.

Reserve halfback Sarel Pretorius gave the passionate, 30,000-strong home crowd some hope with a try in the corner - converted by Berrick Barnes - with six minutes to go. But it was too little too late.