Highlanders halfback Smith on his guard

Halfback Aaron Smith is eyeing another big performance when the Highlanders play the Blues in Dunedin on Friday night.

The 23-year-old Smith, in his second Super Rugby season, has again been preferred to 51-Test All Black Jimmy Cowan in the No.9 jersey.

That makes it six times in eight games so far this season, but he knows he has to continue to justify his inclusion.

"One of the goals for me this year was to make the 22 for the Highlanders and then the starting line-up, but it's a week-to-week thing," he said.

"I have to play well each game. I'm trying to stay focused and grounded. Jimmy and I are battling it out and I'm really enjoying that contest."

Smith said the pair had an excellent relationship despite the keen rivalry and Cowan had been supportive of him.

"That reflects in the way we help each other out," he said.

"He's been huge. He's one of the first to say, 'You're going well, mate', and I'm really chuffed about that."

Cowan, who announced this week he had signed a two-year deal with English club Gloucester, said he remained committed to the Highlanders until the end of the season and would do all he could to help Smith.

"I think he's playing well," Cowan said.

"He's a great young fella, always asking questions, and I'm happy to answer them."

Coach Jamie Joseph has made two personnel changes to the 15 that started the 21-6 loss to the Stormers before their bye last weekend.

Outstanding fullback Ben Smith has been ruled out by concussion and is replaced by Tamati Ellison who moves from centre, with Phil Burleigh elevated from the reserves to the No.13 jersey.

Mike Delany, who has gained clearance from Japanese club Panasonic Wild Knights, will slot straight in at first five-eighth in place of Chris Noakes, who drops to the bench.

Delany will be the fourth player the Highlanders have used in the position this year, after Noakes and the injured Colin Slade and Lima Sopoaga.

The Highlanders sit fifth on the competition ladder, while the Blues are second last, but they haven't beaten the northerners since 2006.