New South Wales Waratahs centre Rob Horne and scrumhalf Jake Gordon have been called into the side for tests against Fiji, Scotland and Italy.
"It's really unfortunate for Samu and Nick but a great opportunity for Jake and Rob to come into the squad," Cheika said. "Rob has been a strong leader in our Wallabies environment and his experience will be invaluable in this relatively inexperienced squad."
Kerevi was injured while playing for the Queensland Reds against the Auckland Blues in Samoa on Friday, while Phipps missed the Waratahs' clash with the Waikato Chiefs on Saturday after he was injured last week.
Neither player will require surgery but the injury to Phipps in particular has exposed a worrying lack of depth for the Wallabies in the number nine jersey.
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Gordon and the ACT Brumbies Joe Powell are both uncapped, leaving veteran Will Genia as the only specialist scrumhalf with any test experience.
Cheika, however, backed his young players to step up for the Wallabies, whose biggest test during the June series is likely to come from a Scotland side that have lost just three players to the British and Irish Lions tour.
"Jake was involved in our camp in Canberra earlier this year and has really stepped up for the Waratahs in Super Rugby," Cheika added of Gordon's elevation into the squad.
"He's another uncapped player but it will be good to expose him to the test environment.
"We really want to put a strong emphasis on leadership in this team and we have some young leaders in this squad who are continuing to develop."
(Reporting by Greg Stutchbury in Wellington; Editing by Peter Rutherford)
