All Blacks halfback Jimmy Cowan has been dropped to the bench in one of four changes to the Highlanders' starting team to face the NSW Waratahs in a must-win Super Rugby match in Sydney on Saturday night.

Cowan makes way for young halfback Aaron Smith, while veteran five-eighth Tony Brown gets a start alongside the new No.9 after being named as Lima Sopoaga's replacement.

Sopoaga is representing New Zealand at the junior world championship in Italy.

In the forwards, Jason Rutledge comes back into the starting 15, replacing Mo Schwalger, who moves to the reserves, while prop Bronson Murray joins Rutledge in the front row with Chris King moving to the bench.

After back-to-back home losses to the Lions and the Force, coach Jamie Joseph's eighth-placed Highlanders must beat the Waratahs and win their final match, away to the Blues next week, to have any chance of making the top six playoffs.

Highlanders: Ben Smith, Kade Poki, Kendrick Lynn, Shaun Treeby, Siale Piutau, Tony Brown, Aaron Smith, Nasi Manu, Alando Soakai, Adam Thomson, Josh Bekhuis, Jarrad Hoeata, Bronson Murray, Jason Rutledge, Jamie Mackintosh (captain). Reserves: Mo Schwalger, Chris King, Nick Crosswell, John Hardie, Jimmy Cowan, Robbie Robinson, Telusa Veainu.

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