Centre Richard Kahui, halfback Brendon Leonard and loose forward Sione Lauaki, all with All Blacks experience, were today demoted to the bench for the match in Hamilton.
Replacing them are Jackson Willison, Junior Poluleuligaga and Colin Bourke as part of six personnel changes from the side who began the 49-15 defeat to the Stormers at the same venue last Friday.
"They are senior players and they remain that," Foster said.
"The decision to use the three off the bench is just a strategy to get the best out of players that are fantastic for us. It's just to get them to look at the game in a different way."
Foster agreed with the assessment that neither Kahui, Leonard nor Lauaki had produced their best so far this season.
But it wasn't for lack of trying, he added.
"Brendon and Richard have carried a pretty big load for us so far," he said.
"It's a chance to freshen them up a bit and to give them another challenge. It's also designed to get a bit more of an edge to their game."
Lauaki, meanwhile, had had a season disrupted by suspension for a dangerous tackle and a court appearance after an altercation in a Hamilton bar.
Foster said Lauaki's physical defence and the way he had carried the ball over the past two weeks had been "fantastic", but mistakes in his game had been an issue.
"In the first 20, 25 minutes against the Stormers, I think Sione was offside twice, he made a handling error...it's those little errors early in the game where we are trying to gather our own momentum that just hindered us a little bit," Foster said.
"He's a very proud Chief. I know it hurts him to be on the bench but, right now, I think it's the best thing for him."
In other changes, All Blacks flyer Sitiveni Sivivatu returns from a knee strain, balancing the loss of fellow-winger Lelia Masaga for three to six weeks, also to a knee problem.
Callum Bruce comes into second five-eighth, with test back Stephen Donald moving inside to his more usual No 10 jersey to replace Mike Delany, who needs shoulder surgery and will be out for up to six months.
In the front row, Nathan White is elevated from the bench to tighthead prop in a straight swap with Ben Afeaki.
While Masaga and Delany have been added to the Chiefs' casualty ward, lock Kevin O'Neill and prop James McGougan have got over Achilles and back problems respectively to be included on the bench.
Defeats in successive weeks to the Bulls and the Stormers mean the Chiefs are still looking for their first win of the year in Hamilton, having struck out at Waikato Stadium a total of four times.
They sit back in 10th spot, just three places above the second-bottom Cheetahs, and nine points below the top four with just four matches remaining.
However, skipper Liam Messam hasn't given up on a miracle run into the semifinals.
"Anything can happen in this competition," he said.
"The excitement levels and the energy the boys have shown during this week is a good sign. The belief is still there. It's going to be tough to get out of it, but we love the challenge we are in."
