Bay of Plenty prop Aidan Ross and Counties Manukau halfback Jonathan Taumateine come into the Super Rugby squad, after Graham (fractured tibia and fibula) and Weber (fractured femur [thigh bone]) were ruled out for six months after both picking up leg injuries at last weekend's Brisbane Global Tens.
Ross, 21, was a member of the victorious New Zealand side at the 2015 World Rugby Under-20 Championship, while 20-year-old Taumateine - who featured for the Chiefs at the Tens - was a member of the side which finished fifth at the corresponding under-20 tournament last year, having represented Samoa the year before.
The Chiefs' loosehead side will be shored up by Kane Hames, who made his All Blacks debut last year, with Siegfried Fisi'ihoi another option who Ross will be trying to jostle for game time.
In the halfback stakes Tawera Kerr-Barlow will be relied upon more heavily now, while Tasman's Finlay Christie will be eyeing a debut in his first season of Super Rugby, with Taumateine providing a third option, after Kayne Hammington this year joined the Highlanders.
The Chiefs have also added 24-year-old Counties Manukau lock Matiaha Martin to their ranks, as cover for the non-contracted Fin Hoeata, who suffered ankle ligament damage at the Tens which will sideline him for two to three months.
Following their 28-7 loss to the Bulls at Ballymore, and then their victory in the inaugural Tens event, the Chiefs' final pre-season hitout is against the Blues in Auckland on Friday evening, where the team's All Blacks are set to return to action.
The Chiefs open their campaign against the Highlanders in Dunedin next Friday.
Photo: DIANNE MANSON/GETTY IMAGES (Prop Aidan Ross has been called into the Chiefs squad after Mitchell Graham's season-ending injury).