He has suffered a high ankle sprain and is out for a considerable time.
Highlanders assistant coach Clarke Dermody said Ainsley rolled his ankle last Thursday and was a late withdrawal for the match against the Crusaders in Temuka on Friday night.
It was a serious injury, needing surgery, meaning he was unlikely to be sighted for the Highlanders this season.
Ainsley (25) went to Otago Boys’ High School and then moved to Australia where he played Super Rugby and was capped by the Wallabies.
He returned to the Highlanders this season. Dermody said it was hard on Ainsley, who had impressed in pre-season and was looking good.
Fellow prop Ayden Johnstone suffered a concussion in the game between North and South in September and was still going through protocols to return to the field. He was back training but there was no timeline on when he returned properly.
The Highlanders have seven props in their squad and will need them all. Veteran front rower Josh Hohneck played well on Friday night and Dermody said he was an asset both on and off the field.
The Highlanders are scheduled to play the Hurricanes in their final pre-season game this Friday.
Dermody said the All Blacks were allowed to play 40 minutes this week. Liam Squire was not far away from being ready but was unlikely to play.
Dermody felt in the first half at Temuka, the Highlanders had impressive intensity, the team had nailed its attack, and the defence was strong. The Highlanders led 26-0 at halftime before going down 28-26.
