Canberra Raiders coach Ricky Stuart has sprung a selection surprise by elevating Sam Williams into the starting halves and confirming Siliva Havili will start at hooker in his club's only trial of 2018.

Star five-eighth Blake Austin will start Saturday's trial against the Canterbury-Bankstown Bulldogs from an extended bench that will also include Craig Garvey. The former Dogs rake is battling Havili to replace injured Englishman Josh Hodgson in the team for round one of the Telstra Premiership.

Williams's return from the Super League to bolster the club's playmaking stocks had been expected to place added pressure on the regular halves Austin and Aidan Sezer, as was the case during Canberra's giant-killing run of 2016.

Stuart indicated at Friday's captain's run that Austin would play in the halves alongside Williams when he is first introduced from the bench, pushing Sezer into dummy-half duties, while Garvey would also get a run at hooker in the second half.

With Kurt Baptiste forced out of the Raiders roster due to salary cap pressure, a utility role has also opened up on the bench this year and Stuart plans to field a number of different spine combinations on Saturday night.  

Canberra Raiders half Sam Williams. ©NRL Photos

"They've all trained well and we know now what our combinations can be," Stuart said of his playmaking options.

"There's two or three different possibilities so the trial will actually help me now make some decisions there around game one.

"I'm mixing around a few combinations to try and give us an opportunity to exercise and find out who our best combination is going to be."

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Canberra's clash with the Bulldogs, coached by former Raiders assistant Dean Pay, is their only pre-season fixture before their round one clash with the Gold Coast Titans on March 11.

The shortened pre-season ups the ante when it comes to Stuart's team sheet, as skipper Jarrod Croker welcomed the competition for starting spots once more in the nation's capital.

Last season's fall out of semi-final reckoning coincided with the exits of a number of fringe players from Canberra, including Paul Vaughan (Dragons), Shaun Fensom (Cowboys), Edrick Lee (Sharks) and his cousin Brenko Lee (Bulldogs), Frank-Paul Nu'uausala (Wigan) and Williams (Wakefield).

All were forced elsewhere in pursuit of regular game time as a result of the club's enviable roster depth just 18 months ago.

With pressure on a number of off-contract individuals to perform, Croker has seen the scrambling for positions intensify over the Raiders pre-season.

"There's plenty of competition for spots at the moment," Croker said.

"We've got depth around the halves, plenty in the forwards and obviously that No.9 jersey is up for grabs. It's good for those boys to put their best foot forward."

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