Improvements in their injury list, and their lineout performance against the Fijian Drua at the weekend, have boosted the Highlanders ahead of their game with Moana Pasifika on Friday in Auckland.

Assistant coach Tom Donnelly said loose forwards Shannon Frizell, Marino Mikaele-Tu'u and hooker Andrew Makalio could return to the selection frame. At the same time, second five-eighths, Thomas Umaga-Jensen has recovered from a hip complaint.

But as a lineout operator in his playing career, Donnelly probably took more satisfaction from the improved lineout effort against the Fijians.

"We struggled early on, and the lads have put in a lot of hard work to fix some of the fundamental issues we were having.

"We nailed our basics well, which gave us the opportunity to get some clean lineout ball.

"It's a bit of a line in the sane because it's where we need to be every week in this competition."

The players were not the only ones who had been working hard. Donnelly has also been part of All Blacks forwards coach Jason Ryan's session with Super Rugby forwards coaches earlier in the year.

"The main purpose of that was to get alignment around 'this is how the All Blacks are trying to do things this year'. And then, it was mainly to chew the fat on trends around the lineout, the maul, stopping the maul, what they noticed at the end-of-year tour last year, and what we can take from other teams around the world.

"A lot of the forwards' coaches now have all either played together or against each other or have been involved for a few years.

"It was mainly around the maul, how you set that up and how you stop it. There was a big conversation around the rules, and how the referees are interpreting that, with back-lifters and the positions they're getting to."

What was a constant was the evolution in the game.

"You always have to be trying to be ahead of the game, because just as you're trying to fix something, someone's going to come up with something different. So, you just need to be adaptable."

Contact with Ryan and the other coaches resulted in Donnelly working hard on apparent issues with the Highlanders' lineout. And the benefits were seen against the Fijian Drua when Will Tucker was handed the calling duties. But the lineout was always a moving feast, and it took more than improvement in one area to make a change.

"If there was one simple answer, I think lineouts could be solved pretty easily. But there are so many moving components to align.

"Timing is one, lifting technique, jumping technique, jumping in the right spot, hookers getting the timing right. So, it's a process of elimination."

Donnelly was confident that there was life after Sam Whitelock and Brodie Retallick, both expected to sever their New Zealand ties after this year's Rugby World Cup.

Some locks had been around the New Zealand scene for some time, and players coming through the Under-20s system.

"You can't coach height, so we're probably lucky enough that we have some tall timber around the country at the moment."

The Highlanders take on Moana Pasifika at 7.05pm NZT, Friday 31 March, at Mt Smart Stadium.