Roma coach Rudi Garcia slammed Senad Lulic for his dangerous tackle on Mohamed Salah during Lazio's 2-0 loss on Sunday.
Lulic avoided sanction despite stomping on Salah's ankle, leading to the 23-year-old being substituted before the hour-mark at the Stadio Olimpico.
Garcia was angered by the challenge and said he would be shocked if Salah had avoided serious injury.
"We just hope there's no break," he said.
"You've seen the images so there's not much else to say. Tackles like that don't belong, not even in the derby.
"We need to protect the players and keep them safe. I hope it's not too serious for Salah, but it'll be a miracle if there's no break or fracture."
Roma went ahead through Edin Dzeko in the 10th minute, with the striker converting a controversial penalty.
The Bosnia-Herzegovina international appeared to be brought down outside the area by Santiago Gentiletti, but a spot-kick was awarded.
Garcia, whose team sealed their win through Gervinho, said it was a close call.
"If it's the foot that commits the foul – and I don't think it was – then it's outside of the area, but if you consider the knee as the body part committing the foul then it's on the line and a penalty," he said.
"That said I just want to speak about football and not about decisions. Whether it was a penalty or not changes nothing about our win."
