Ben Smith is checked over after he was knocked out in the first half of his team's 24-15 loss to the Chiefs last week.

Highlanders fans crossing their fingers in hope of fullback Ben Smith making a swift recovery from concussion might well be disappointed.

The 30-year-old was knocked out after landing on his head against the Chiefs in Dunedin last Friday, and has been replaced by Richard Buckman for the team's second round game against the Crusaders on Saturday night.

He was always expected to miss at least one game but, given it's the All Blacks co-captain's fourth concussion in the past five years, coach Tony Brown said a cautious approach was needed.

HANNAH PETERS/GETTY IMAGES Richard Buckman will start at fullback in place of Ben Smith on Saturday night.

"Concussions are always week-by-week," Brown said. "He hasn't even been able to come in to training this week.

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​"He's OK, but obviously with concussion you never know how long it's going to take. We're going to be pretty cautious with Ben and just bring him back when he's 100 per cent."

ROB JEFFERIES Elliot Dixon will captain the Highlanders against the Crusaders.

The fullback last missed game time due to a concussion last year, when he sat out two weeks after taking a knock against the Force.

Smith's unavailability is partially offset by the return of Buckman for the all-important South Island derby at Forsyth Barr Stadium.

The 27-year-old, affectionately known as "The Barracuda", hasn't started a competition game for the Highlanders since the 2015 Super Rugby final triumph against the Hurricanes.

SCOTT BARBOUR/GETTY IMAGES Prop Siosiua Halanukonuka has replaced Siate Tokolahi in one of three changes to the Highlanders' stating side for Saturday's game against the Crusaders.

He suffered a season-ending shoulder injury in a pre-season match against French club Racing 92 last year, but recently completed a season in Japan.

Brown said he intended to bring Buckman back into the mix off the bench this week, before Smith's injury forced his hand.

"He obviously missed all last year and he was sorely missed," Brown said. "That year [2015] he had before that was outstanding, so not to have him last year was a big blow to our campaign."

Brown said the decision to go with Buckman, who shone in the midfield in 2015, at fullback instead of Matt Faddes was largely due to his decision making.

"We just felt Richard has the uncanny ability to make the right decision at the right time. And his physicality at the back is something we wanted to get into play against the Crusaders."

Faddes has been replaced by winger Patrick Osborne in the match-day 23 and will play at centre for the Highlanders development team against the Crusaders Knights on Saturday.

With co-captains Smith and Ash Dixon (back) both included on a lengthy injury list, loose forward Elliot Dixon will captain the Highlanders on Saturday.

Dixon came off the bench in last week's 24-15 loss to the Chiefs and has swapped places with blindside flanker Gareth Evans this week.

"When Elliot speaks, everyone listens," Brown said. "His leadership style is just going to be one of action and we're hoping he will have a big game for us and lead in that way."

Lock Joe Wheeler, who also recently completed a season in Japan, has been rushed on to the bench a week earlier than planned to provide extra leadership in the second half.

Brown said including Wheeler this week was needed with Smith, Dixon and veterans Luke Whitelock (shoulder) and Shane Christie (illness) unavailable.

The first-year Highlanders head coach still couldn't shed any light on Christie's mystery illness, only that his status was week-by-week.

"I've got no idea. That's just a wait and see that one," he said.

After the Dunedin-based franchise was denied a single try in a match for the 20th time in their history last week, Brown has only made one other change to his starting side, with Siosiua Halanukonuka set to run out in the No 3 jersey in place of Siate Tokolahi.

"Obviously pretty disappointed to get 65 per cent territory and 60 percent possession and not even score a try," Brown said.

"It was a frustrating day at the office for us last week and we're obviously focussing on being a bit better this week."

AT A GLANCE

Highlanders v Crusaders

Forsyth Barr Stadium, Dunedin

Saturday, 7.35pm

HIGHLANDERS: Richard Buckman, Waisake Naholo, Malakai Fekitoa, Rob Thompson, Tevita Li, Lima Sopoaga, Aaron Smith, Liam Squire, James Lentjes, Elliot Dixon (c), Tom Franklin, Alex Ainley, Siosiua Halanukonuka, Liam Coltman, Daniel Lienert-Brown. Reserves: Adrian Smith, Craig Millar, Siate Tokolahi, Joe Wheeler, Gareth Evans, Kayne Hammington, Fletcher Smith, Patrick Osborne.

CRUSADERS: David Havili, Israel Dagg, Josh Goodhue, Ryan Crotty, Seta Tamanivalu, Mitchell Hunt, Bryn Hall, Whetu Douglas, Matt Todd, Jordan Taufua, Sam Whitelock (c), Scott Barrett, Owen Franks, Codie Taylor, Joe Moody. Reserves: Ben Funnell, Wyatt Crockett, Mike Alaalatoa, Luke Romano, Jed Brown, Mitchell Drummond, Marty McKenzie, George Bridge.