But the Australia-Tonga forward will miss anywhere from a week to a month as he has severe swelling on the knee and some bone bruising.
In other news to lighten coach Shane Flanagan's mood, his other starting prop Matt Prior has escaped suspension and can play against Penrith next Sunday at Southern Cross Group Stadium.
The match review committee issued a grade one charge and $1500 fine, which reduces to $1350 if he pleads guilty early. Prior would then be free to play the Panthers.
"That's massive news for us," Flanagan told NRL.com.
"In regards to Andrew, his ACL has not been damaged but he's got no PCL (posterior cruciate ligament), or the little he had left of that has torn.
"It means his knee is unstable and went from underneath him because of not having that PCL. So the first diagnosis (suspected torn ACL) was wrong, thank god.
"He does have some bone bruising so we have to see how that settles over the next couple of days and by Tuesday I'll have a better idea.
"At this stage he could be right next weekend or he could be out for a month."
However, the Sharks will be without both their co-captains in Paul Gallen and Wade Graham for the clash with the Panthers in round seven and then the Gold Coast in round eight, at least.
Gallen is due to have scans Sunday on his right knee, which he had in a leg brace after Friday night's 40-20 loss to St George Illawarra. Graham has a left hamstring strain, which was scanned on Saturday, and that will be anywhere from two to four weeks.
He could be right next weekend or he could be out for a month.
Shane Flanagan on Andrew Fifita
"Hamstrings are tricky things so it's not good to give a definite comeback week," Flanagan said.
"And while Gal hasn't been scanned yet, we're pretty sure it's medial ligament damage so depending on a grade one tear, grade two or three, that will determine how long he is out. But we know he's out for the next couple of weeks."
Luke Lewis has a corked knee after a collision with former Shark Jeremy Latimore and could miss next week's match against his old club, the Panthers.
"It's probably a week but we're going to race him and see if we can get it right," Flanagan said, hoping that Lewis would heal quickly with intense treatment.
Flanagan spoke to NRL.com while at Cessnock in the NSW Hunter Valley watching the Sharks Intrust Super Premiership feeder club, Newtown Jets, play Newcastle.
The forward replacements Flanagan needs will come from the Newtown squad.