The more experienced James Wilce and Sean Martin will sit out the round.
Nick Beamish, 12, is currently ranked top seed nationally in the under-16 age group, ahead of elder brother, and second seeded, Ryan.
Despite Cambridge's low ranking on the ladder in both grades, Tamai is not taking any chances.
"We're not taking them lightly but it is perfect opportunity to let the younger players get involved and see how they can measure up," Tamai said.
The younger Beamish had been displaying good form in previous games and deserved his chance, he said.
"He's only 12 years old but is playing like a much older player."
Tamai said it was no surprise the combined Rotorua team was performing well, winning all but one round so far.
Tamai has only been beaten once in the competition - against Otumoetai's nationally ranked Austin Childs 6-2, 6-3.
"We are stronger mentally this year with some of the old heads showing their experience," he said.
Rotorua Lynmore women also travel to Cambridge to play the home team which is ranked fifth.
The playing squad will be chosen from Pang Suwanaposee, Zanna Douglas, Weiwei Verran, Leona Davis-Kaye (captain), Aliya Edwards, Debra Dowland, Lara Wild, and Tia Van Selm.