Leonard injured his hamstring in the round-one loss to the Highlanders and has watched on as Tawera Kerr-Barlow and Augustine Pulu have tried to establish themselves, with some degree of success, at this level.
There are several changes between numbers one and eight.
Alex Bradley has given way to Samoan international Kane Thompson at the back of the scrum, while they will experiment once more with a left-right flanker combination of Sam Cane and Tanerau Latimer.
Liam Messam sits out with a rib injury.
In the second row, Manawatu's Mike Fitzgerald gets a start alongside captain Craig Clarke. The impressive Brodie Retallick gets his first rest of the tournament.
To the undoubted disappointment of the crowd, Sona Taumalolo will be restricted to a role off the bench as he attempts to add to his season-leading seven tries.
The rarely-used Scott Waldrom, Jackson Willison and Maritino Nemani will join the reserves.
"As we are only halfway into the competition we are using this game to give some players who have not had much game time an opportunity they deserve," Rennie said.
It's a tricky balancing act. Even against a team like the Lions, which has no pedigree of success in New Zealand, there is a danger that too many changes smack of hubris.
It's been a red letter week for the Chiefs so far, after it was announced that assistant Wayne Smith had committed to the end of his contract in 2013.
About the only thing that could improve their outlook would be the signature of a certain second five-eighths, named to start alongside Richard Kahui.