Lee said Acton would be sidelined for 12 to 15 months with the injury.
Lee said he was yet to choose a new captain to lead the side for the rest of the season.
Rotoiti are also likely to be missing another star forward in Joe Royal when the team clash with Greerton Marist at Emery Park tomorrow.
Royal suffered an injury in Rotoiti's win against Te Puke last weekend.
On a positive note for the club, Rotoiti have strung four straight victories together and have given themselves an outside chance of making the semifinals.
Lee said he was unsure what led to the club's drastic change in fortunes.
"I don't know what it was because we have had the same players all the way through.
"It's like a light was switched on, the players understood what we were trying to do and everything started to click," he said.
Meanwhile, Whakarewarewa will look to break their losing streak when they meet Te Puke at Puarenga Park tomorrow.
Opotiki's clash with Mount Maunganui is another match with plenty riding on it.
The teams are in fifth and seventh place on the ladder respectively and are both within one win of Te Puna in fourth place.
In other premier games, Rangataua host Te Puna and league-leaders Tauranga Sports host Paroa.
Division one (all games start at 2.45pm tomorrow):
Kahukura v Rangiuru (Kuirau Park), Katikati v Te Teko (Moore Park), Ngongotaha v Marist St Michael's (Ngongotaha Domain), Poroporo v Whakatane Marist (Poroporo Park), Ruatoki v Waikite (Tuhoe Park).
