The Lions forward line coach says the treatment handed out to skipper Jonathan Brown is against the rules and needs to be stamped out.
The issue flared after Brown was constantly roughed up by Collingwood defender Leigh Brown at the MCG on Saturday night.
Fletcher said the physical treatment is taking a heavy toll on the Lions captain.
"Defenders going beyond the rules is unsettling to my players," Fletcher said.
"If you get belted in the ribs consistently and your kidneys, can you imagine by the end of the game …
"Niggling is fine but when it's a full blow to your lower kidney, what can you do about it? Do you retaliate or do you run off the ground?"
AFL director of umpiring Jeff Gieschen says umpires will be instructed to closely monitor this practice and to pay free kicks where appropriate, as this kind of contact is not within the spirit of the game.
Fletcher agreed: "There's a breaking point and we don't want to get to that stage, we just want free kicks to be paid if it gets to a point where it's unfair.
"But we're not going to fall into the trap of retaliating."
"We've got to make sure we focus on the football; if we do that, the umpires will look after the game."
Fletcher said retaliating was not on Brown's mind, no matter how much he was pushed and shoved.
"He can smell the grass in September," Fletcher said.
"I don't think he's going to retaliate, there's too much up for grabs.
Fletcher says niggling happened in his playing days but the difference then was that players were more likely to retaliate.
"I remember Greg Williams; if somebody punched him, he would threaten if they did that again they would get what they were deserving," Fletcher said.
"He probably got away with it, but you don't get away with anything now with all the cameras."
Lions full-forward Daniel Bradshaw was being put through a rigorous closed session on Wednesday morning to test out his injured hamstring.
Tim Notting's return from suspension will be a welcome one for the Lions as they travel to the MCG for the second week in a row to take on Essendon on Saturday night.
"Notting is an important part to that flexibility in our forward line," Fletcher said.
"If we can get Notting playing his role and hopefully get Bradshaw back, we've got flexibility where we can get goals in four or five areas. The last two weeks we probably struggled in that area."
