Both internationals will miss the Highlanders’ ground-breaking game against Moana Pasifika in Tonga on Saturday afternoon.
Loosehead prop de Groot has an All Blacks-mandated rest week and will be shivering in a Southland mai mai while his team-mates are sweating in Nuku’alofa.
"That’s been planned for a while," Highlanders coach Clarke Dermody said yesterday.
"It’s all part of the plan that we set out at the start of the year.
Daniel Lienert-Brown will enjoy another rare chance to start in the No 1 jersey and fit-again tighthead prop Jermaine Ainsley returns to the bench.
While de Groot’s immediate focus will be the flying birds, Patchell’s Highlanders career appears grounded.
The classy Welsh first five could miss six to eight weeks with his pectoral muscle injury. That means — barring a miracle that leads to the Highlanders making a deep run through the playoffs — his time in New Zealand rugby is done.
"He’s avoided surgery, which is good," Dermody said.
"But it’s still a six to eight-week injury for a pec strain, so depending on when he gets back, and how far we go, we’ll see how it looks."
It means another start for Cameron Millar this weekend.
The young Otago first five has looked at home at Super Rugby level in patches but at times has showed his inexperience.
Dermody and his staff have been eager to foster the development of Millar and fellow rookie playmaker Ajay Faleafaga. They have confidence Millar, who played most of the 7-6 win over the Force on Saturday night, can deal with the literal and metaphorical heat in Tonga.
"What he showed at the weekend, to come on and run the game like he did, I thought he did a great job.
"Generally your 10s are the main driver of the week and he’s done a great job, so we’ve got confidence in him, and we know he’s got a big future for the club.
"It’s not going to be easy but we feel like he’s tracking the right way."
Jake Te Hiwi, despite the return of vice-captain Sam Gilbert to the squad, retains the No 12 jersey.
Dermody felt Te Hiwi acquitted himself well against the Force and offered an exceptional workrate off the ball.
A bit of Dunedin rain yesterday was welcomed by the Highlanders as they prepare to deal with humidity and a sweaty ball on Saturday.
Dermody has actually played a game in Nuku’alofa.
He was in the Junior All Blacks team, alongside Highlanders assistant coach Tom Donnelly and a couple of future All Blacks greats in Kieran Read and Cory Jane, that beat Tonga 39-13 as part of the Pacific Nations tournament in 2007.
Meanwhile, Dermody said there was nothing earth-shattering to report from All Blacks coach Scott Robertson’s visit to Dunedin on Tuesday.
"It was great to have him in. It’s the first time he’s been here.
"Obviously he spent a long time up the road coaching against us, so it was his first time in the building, seeing how we operate, and he had some good feedback for the coaches."
Highlanders team to play Moana Pasifika
Nuku’alofa
Saturday 2.05pm (NZ time)
Jacob Ratumaitavuki-Kneepkens, Timoci Tavatavanawai, Tanielu Tele’a, Jake Te Hiwi, Connor Garden-Bachop, Cameron Millar, Folau Fakatava, Billy Harmon (captain), Sean Withy, Oliver Haig, Fabian Holland, Mitch Dunshea, Saula Ma’u, Henry Bell, Daniel Lienert-Brown.
Reserves: Jack Taylor, Ayden Johnstone, Jermaine Ainsley, Will Tucker, Nikora Broughton, James Arscott, Sam Gilbert, Martin Bogado.