All Black Kaino in doubt for Lions tour
The Blues said the 77-Test flank would be sidelined for about six weeks after going under the knife to fix a torn meniscus.
That puts Kaino in line for a return in early-to-mid-June.
The Lions are due to pay the Blues on June 7 and their first Test against the All Blacks is June 24.
The two-time World Cup winner's absence would be a massive blow for New Zealand, although Blues assistant coach Steve Jackson insisted it was minor surgery that should not affect Kaino's All Black duties.
"I'm pretty sure he'll be fine for the Lions tour," Jackson told reporters.
"He'll get his feet up and [players] normally come back pretty quick from those sorts of operations."
At the very least, the setback will leave Kaino's preparations severely disrupted, forcing coach Steve Hansen to look at alternatives such as Liam Messam, Elliott Dixon and Liam Squire.
Meanwhile, The Blues face the Brumbies in Canberra on Sunday.
Gifted young Maori All Black loose forward Akira Ioane has his opportunity to shine when he starts this weekend.
Ioane has big shoes to fill for his third start of the season at No 8, with inspirational Kaino ruled out.
Coach Tana Umaga said while the loss of Kaino is a blow for the team, it presents an opportunity for gifted Ioane who has played in all eight games this season mostly off the bench.
It is the only change in the pack from the last game against the Hurricanes before the bye, with All Black Steven Luatua moving to his preferred blindside flank role, and Ioane taking over at No 8.
Taranaki and Maori All Black lock Leighton Price, called into the squad this week for the rest of the season as a replacement, will be pressed into immediate action on the bench, with Patrick Tuipulotu, Jimmy Tupou and Josh Goodhue all ruled out with injury.
All Black prop Ofa Tu'ungafasi will reach his milestone of 50 games for the Blues, when he gets a likely call off the bench this weekend, while newly selected English international, Piers Francis reaches his 20th and Blazer game.
Midfielder George Moala is recalled to the starting line-up to form an All Black midfield with Sonny Bill Williams, with Rieko Ioane moving to the left wing.
Blues: 15 Michael Collins, 14 Matt Duffie, 13 George Moala, 12 Sonny Bill Williams, 11 Rieko Ioane, 10 Piers Francis, 9 Augustine Pulu, 8 Akira Ioane, 7 Blake Gibson, 6 Steven Luatua, 5 Scott Scrafton, 4 Gerard Cowley-Tuioti, 3 Charlie Faumuina, 2 James Parsons (captain), 1 Pauliasi Manu.
Replacements: 16 Matt Moulds, 17 Ofa Tu'ungafasi, 18 Sione Mafileo, 19 Leighton Price, 20 Murphy Taramai, 21 Billy Guyton, 22 Bryn Gatland, 23 Melani Nanai.
Date: Sunday, April 30
Venue: GIO Stadium, Canberra
Kick-off: 17.05 (19.05 NZ Time; 06.05 GMT)
Referee: Nick Briant (New Zealand)
Assistant referees: Ed Martin (Australia), Graham Cooper (Australia)
TMO: George Ayoub (Australia)
AFP & @BluesRugbyTeam
