Amatosero was given a four-match suspension in the pre-season for punching Angus Scott-Young in a wild brawl but the ban was halved after he underwent counselling.
He was barred from even turning up to the Waratahs' training base in Daceyville for two weeks but coach Dan McKellar named the 23-year-old in his match-day squad to face Reds.
Waratahs captain Matt Philip said he expected the Reds to bait Amatosero but he was confident the lock would rise above it.
"For sure there’ll be words around it, but I think he’s going to be prepared for that," Philip told reporters on Thursday.
"He knows what’s coming and we’re prepared for that.
"I’ve spoken to him about it, I’ve said: 'This is what’s going to come'. And he goes, 'Yep, that’s fine’.
"I don't think he’s going to have any issues on that front, and he'll show his reaction through the laws of the game of rugby."
Former Queensland and Australia winger Wendell Sailor urged the Reds to use the training fight as ammunition on the field, saying it could prove the difference in a tight game.
"Like all firebrands in any sort of (football) code, you've got to try and bait them," Sailor told Australian Associated Press.
"It adds to the spice of the game and I know in the dressing rooms, you talk about it."
Philip said Amatosero had done a lot of work away from the club and deserved credit for coming back in good condition to be selected for the home game against the Reds at Sydney Football Stadium.
"It was an unfortunate incident but we're training at high intensity," he said.
"You know, people want to perform for this jersey and unfortunate things happen - and it was very unfortunate."