Hayden Triggs has been called up by the Blues to replace Culum Retallick, but their second-row stocks remain in the balance.

Tom Murday, called up to help ease the locking crisis caused by Retallick's season-ending knee injury, has suffered a knee injury of his own. A scan has revealed a patella tendon problem _ another scan will reveal how long he is out for, but it could be for up to 10 weeks, said coach John Kirwan.

"We're a little bit fragile,'' he said. "Tom has had a little mishap with his knee so we're under the pump.''

Kirwan's locking options are now Tom Donnelly, Liaki Moli, Patrick Tuipulotu and Triggs.


Triggs, 31, a former NZ Maori player who has represented the Hurricanes, Highlanders and Chiefs, is in Japan with the Honda Heat and will return to New Zealand to join the Blues in the next few weeks when his season finishes.

"I'm really excited about returning home to join the Blues,'' Triggs said. I had a great time in Japan but I'm looking forward to the challenge of getting back into Super Rugby and giving it another real crack.''

Kirwan said the 2.01m, 108kg lock was the right profile of player he was looking to secure.

"It was important we got the right player to fill the void losing the experience of Culum and we think Hayden really fits that bill,'' Kirwan said. "He's been away in Japan but he's also played a lot of Super Rugby and he'll bring plenty of experience to the side that we need at the moment."

The Blues play the Waratahs in a pre-season match in Sydney on Friday night.