Johnson-Holmes was set to start at tighthead against defending champions the Canterbury Crusaders at Nelson on Saturday.

However, he was bedridden with a fever and other flu-like symptoms and was unable to train Monday or Tuesday. He had improved by Wednesday however, with the extra travel requiring the squad to depart on Thursday, new coach Rob Penney erred on the side of caution.

Tetera Faulkner comes in at tighthead alongside new hooker Robbie Abel and Wallabies loose head Tom Robertson. Chris Talakai, who conducted a coaching clinic in Newcastle on Tuesday, is the new prop on the bench.

Johnson-Holmes played loosehead last season, while Robertson was recovering from a knee reconstruction and had a breakthrough season, highlighted by a Wallabies debut against South Africa.

With the departure of Wallabies veteran Sekope Kepu, the 22-year-old Novocastrian has switched to the other side of the scrum and had performed well in the pre-season.

Fellow former Wanderer Andrew Tuala, was not selected in the 23-man squad for the trip across the Tasman. It will be the second time Johnson-Holmes has played for the Tahs in Newcastle and follows a 31-29 loss to the Sunwolves last year. Tuala was in the squad but didn't take the field.

AAP reports: Penney has declared complete confidence in his Super Rugby rookies, after opting to blood debutants Will Harrison and Mark Nawaqanitawase in a tough season opener against three-time defending champions the Crusaders.

Five-eighth Harrison and winger Nawaqanitawase will be part of a Waratahs team striving to end the Crusaders 31-game home winning record on Saturday in Nelson.

"A hundred per cent they are ready to go, we wouldn't have compromised their development if we didn't believe they were of stern enough stuff mentally or physically," Penney said.

There are two more 2019 Junior Wallabies and potential Super debutants on the bench in prop Angus Bell and back-rower Carlo Tizzano.

Penney wasn't tempted to put experienced utility back Kurtley Beale at five-eighth, naming him at fullback and placing his faith in Harrison to steer the side around.

"We're not expecting a performance that you would go without error on the weekend because he's being thrust into a tumultuous sort of position, but we trust that he'll do a really good job," Penney said of the playmaker.

"He's got resilience, physically he's a robust character.

"He put himself in tough positions, he'll put his head in dark places. He's prepared to do that for the team, which is a fantastic attribute for someone defending in the inside channels."

A couple of recruits will make their Waratahs Super Rugby debut as starters, hooker Robbie Abel and prop Tetera Faulkner, the latter getting his chance after Harry Johnson-Holmes fell ill.

Wallabies World Cup squad member Jack Dempsey, who has had a couple of injury setbacks in the pre-season, will come off the bench with Lachlan Swinton named as the starting blindside flanker.

Penney opted for six forwards on the bench, with recently signed Wallaby Jack Maddocks one of two backline replacements.

Waratahs: Kurtley Beale, Mark Nawaqanitawase, Lalakai Foketi, Karmichael Hunt, Alex Newsome, Will Harrison, Jake Gordon, Jed Holloway, Michael Hooper, Lachlan Swinton, Rob Simmons (capt), Tom Staniforth, Tetera Faulkner, Robbie Abel, Tom Robertson. Reserves: Chris Talakai, Damien Fitzpatrick, Angus Bell, Ryan McCauley, Carlo Tizzano, Jack Dempsey, Mitch Short, Jack Maddocks.