The told the Blues' official website.
"The Crusaders are the benchmark in New Zealand rugby, so we are under no illusion about the task ahead of us. They have won the last 35 games of Super Rugby at home.
"Just because we have won the last three games, we know that means nothing in the scheme of things.
"We know that we will need to be very accurate with and without the ball while the battle in the forwards for clean front-foot possession with be a key.
"If we can implement our game plan and execute, then there is no reason why we can't provide a stern test. And if the weather plays ball, it should be a cracking game."
MacDonald said Christie earned his start after excellent performances off the bench and he will renew his combination with fellow former Hurricanes backs Otere Black and Beauden Barrett.
Plummer is an excellent all-round player who adds yet another kicking option and allows 41-game midfielder TJ Faiane to come off the bench after playing big minutes in this competition.
15 David Havili, 14 Sevu Reece, 13 Braydon Ennor, 12 Jack Goodhue, 11 George Bridge, 10 Richie Mo'unga, 9 Bryn Hall, 8 Whetu Douglas, 7 Tom Christie, 6 Tom Sanders, 5 Mitchell Dunshea, 4 Sam Whitelock, 3 Michael Alaalatoa, 2 Codie Taylor (captain), 1 Joe Moody
Substitutes: 16 Andrew Makalio, 17 George Bower, 18 Oliver Jager, 19 Quinten Strange, 20 Sione Havili, 21 Mitchell Drummond, 22 Fetuli Paea, 23 Will Jordan
15 Beauden Barrett, 14 Mark Telea, 13 Rieko Ioane, 12 Harry Plummer, 11 Caleb Clarke, 10 Otere Black, 9 Finlay Christie, 8 Hoskins Sotutu, 7 Dalton Papalii, 6 Akira Ioane, 5 Josh Goodhue, 4 Patrick Tuipulotu (captain), 3 Ofa Tuungafasi, 2 James Parsons, 1 Alex Hodgman
Substitutes: 16 Kurt Eklund, 17 Karl Tu'inukuafe, 18 Sione Mafileo, 19 Aaron Carroll, 20 Blake Gibson, 21 Jonathan Ruru, 22 TJ Faiane, 23 Matt Duffie