All Blacks return for Blues
Both missed last week with niggling injuries, although the squad still has 12 players unable to be considered for selection.
Northland's Josh Goodhue earns a second start while fellow Taniwha Kara Pryor will add speed in the loose in his first start of the season after injury.
Scrumhalf Jonathan Ruru is rewarded with good form for his first start, with George Moala, powerful last week, moving to the wing in place of the injured Melani Nanai, which allows TJ Faiane to start in the midfield with Rieko Ioane.
Duffie is still bracketed on the wing with Jordan Hyland to be decided after Thursday's final training session.
Northland captain Matt Moulds will come off the bench, returning after off-season surgery, as will former NZ Under-20s players Dalton Papalii and Orbyn Leger.
The Blues were edged 21-27 by the Chiefs in their third-round clash earlier in the season.
Blues: 15 Michael Collins, 14 Matt Duffie/Jordan Hyland, 13 Rieko Ioane, 12 TJ Faiane, 11 George Moala, 10 Stephen Perofeta, 9 Jonathan Ruru, 8 Akira Ioane, 7 Kara Pryor, 6 Jerome Kaino, 5 Josh Goodhue, 4 Patrick Tuipulotu, 3 Ofa Tu'ungafasi, 2 James Parsons (captain), 1 Pauliasi Manu.
Replacements: 16 Matt Moulds, 17 Ross Wright, 18 Mike Tamoaieta, 19 Gerard Cowley-Tuioti, 20 Dalton Papali'i, 21 Sam Nock, 22 Bryn Gatland, 23 Orbyn Leger.
Date: Saturday, April 7
Venue: Waikato Stadium, Hamilton
Kick-off: 19.35 (07.35 GMT)
Referee: Paul Williams (New Zealand)
Assistant referees: Brendon Pickerill (New Zealand), Glen Jackson (New Zealand)
TMO: Aaron Paterson (New Zealand)
