Hardie limped from the field of the trial match between the Highlanders and a Southland Invitational XV last night, a game won by the Highlanders 26-24.
Highlanders coach Jamie Joseph said though it was too early to assess the extent of the injury, it was a worry.
''To me that was the only negative to come out of the game. He can walk around on it, he's got no history there with that sort of injury, so we hope it is not too bad,'' he said.
''That was a game that we really needed. They were a typical Southland team, really tenacious and competed for everything.
''That was led by our players in their team. They scored their tries from mistakes that we made but the physicality they provided really gave us a good taste of what was needed.''
He was happy with the performances of players coming back from injury, such as Buxton Popoali'i and Lima Sopoaga.
The Southland side, which was made up of Highlanders players and Southland representatives, had a chance to win the game in the final minute, but Sopoaga was astray with a 40m penalty.
It was a match which had trial marked all over it, and the Highlanders players showed plenty of rust and inaccuracy at times.
Missing all their All Blacks, the Highlanders were too eager but that is often the case in games like this.
The game was loose throughout and there were some soft tries conceded.
Tony Ensor was a mixed bag at fullback for the Highlanders, scoring the first try but then giving the ball away to allow Southland its opening five pointer.
Nippy Dunedin halfback Brad Weber made the most of his opportunity and scored an opportunist try for Southland early in the second half, kicking the ball through, and diving on it in the nick of time, as the ball appeared to be drifting over the sideline.
The Highlanders were staring at defeat with five minutes to go but halfback Frae Wilson burrowed over by the posts and Hayden Parker kicked the conversion to win the game.
Shaun Treeby had a strong game in the midfield for the HIghlanders while Jake Paringatai was praised by Joseph for making some big hits.
Up front, Brad Thorn was as steady as ever while Jarrad Hoeata got through plenty of work.
Hayden Parker looked good when he came on in the second half, while Popoali'i was as busy as ever Hardie was the best for Southland, young first five-eighth Scott Eade showed his potential and veterans David Hall and Jason Rutledge were industrious.
The Highlanders take on the Crusaders at Forsyth Barr Stadium next Saturday night.
Trial match: The scores
Highlanders ... 26
Tony Ensor, Buxton Popoali'i, Hayden Parker, Frae Wilson tries; Colin Slade 2 cons, Parker con
S'land Invitational XV ... 24
Keanu Kahukura, Warrick Lynn, Brad Weber, Sven Penwarden tries; Scott Eade con, Lima Sopoaga con
Halftime: 14-12 Highlanders
Crowd: 200
