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Attacking opportunities … Berrick Barnes, pictured at training yesterday, is determined to be adventurous against the Bulls on Friday. Photo: Steve Christo

THE Waratahs' South African halfback Sarel Pretorius has told his teammates the only way to beat the Bulls is to be physical - and the selectors have responded by bolstering their arsenal for Friday night's game at Allianz Stadium.

While originally considering playing Daniel Halangahu at inside-centre, it now appears Adam Ashley-Cooper will be in the No.12 jumper in a new look Test-quality centre combination with Rob Horne that will improve the team's directness and defensive capabilities.

Halangahu is instead expected to start at fullback, with centre Tom Carter and halfback Brendan McKibbin the major casualties in a reshuffled back line.

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Sarel Pretorius ... ready for Bulls. Photo: Steve Christo

Waratahs captain and blindside breakaway Rocky Elsom will also be involved in his first starting game of the season, while back-rower Chris Alcock returns from injury to improve the team's scavenging abilities after they failed to counter the Brumbies No.7 Michael Hooper at the breakdown last Saturday night.

Their biggest casualty upfront is Test hooker Tatafu Polota-Nau, who will be rested after suffering several head knocks, with John Ulugia taking over and new signing Josh Mann-Rea coming onto the bench.

While Ashley-Cooper is best known as an outside-centre, winger or fullback, he has played Test football at No.12, and looked extremely comfortable outside five-eighth Berrick Barnes at training yesterday.

The Bulls, who are playing a far more expansive game this season, will also have a new midfield combination, as their Springbok inside-centre Wynand Olivier is doubtful due to a rib injury, prompting a likely Francois Venter-Johann Sadie midfield partnership.

Deon Stegmann is expected to replace the injured Jacques Potgieter in the back row, while Dawie Steyn is scheduled to come in for prop Dean Greyling, who has returned home.

Pretorius, who will return to the Waratahs starting line-up after five games coming off the bench, is familiar with the Bulls style and philosophy, as he hails from the nearby Free State province on the South African highveld. He knows brawn and brain is required to shackle them.

''You just have to match them physically and keep contesting. They are quite structured as well, which is based around kicking in the air. So we just have to protect our wingers, and go from there,'' Pretorius said yesterday.

Thrusting out the chest and going head on was also emphasised by Barnes yesterday.

''You've got to score points to beat the Bulls, because they're a side that once they get inside your 22-metre they are very hard to stop, as they always appear to have 130-kilogram players right across the park. But they've leaked their fair share as well. So we're backing ourselves,'' he said.

Barnes admitted there were a few ''ifs'' surrounding the rejigged Waratahs attack. ''It will be a big test for us to see how we gel, as we only have a few sessions before the Bulls match. Still, we've got to change something because what we've been doing hasn't really been coming to fruition. Hopefully on Friday night we can make it work,'' he said.

Nonetheless, Barnes wants to remain adventurous, especially after being more willing to attack the gain line in Canberra.

''The problem was we'd run from our own half and get to the 50-metre and then turn it over nine times out of 10,'' he said. ''Silly errors cost us, while their pressure at the breakdown … became a turning point.''