The side were awaiting scans to see if the injury was a sprain or something worse but Sopoaga believed he would be back in two weeks, after the Highlanders have their second bye next round.
"I'm all good, not my Achilles. Probably just gout," he joked on Twitter. "Back at it in two weeks."
The injury allowed young first-five Fletcher Smith an extended run in the middle, which saw him line up nicely in the spine of the attack with halfback Aaron Smith and fullback Ben Smith.
The Smith spine could be a feature of the side's starting 15 when 2019 rolls around, with Sopoaga heading offshore.
Fletcher Smith's presence on the field saw the Highlanders more competitive in the territory game, and Mauger noted the reserve first-five was a big reason they were in a position to win the game in the dying stages.
"Hats off to the young man, he did well."
The Highlanders weren't able to pull it off, though, with the Chiefs coming away with a five-point win.
Chiefs coach Colin Cooper said while happy with the result, his side had plenty to work on, particularly their defensive kicking game.
Chiefs No 10 Damian McKenzie was twice charged down when trying to clear late in the second half, the second leading to a Highlanders try.
"There was plenty in the second half that was frustrating for all of us and we didn't exit as well as we could have," Cooper said.
"There's a lot to work on, but we won - I couldn't be happier."
While the Highlanders now go into a week off, the Chiefs prepare for another New Zealand derby, hosting the Blues next week.
