Both Rangers and Celtic ended with 10 men as they fought out an enthralling Scottish Cup fifth-round draw at Ibrox.
The home side took the lead inside three minutes from a wonderful strike by teenage midfielder Jamie Ness.
Kris Commons equalised on 17 minutes, before Celtic goalkeeper Fraser Forster was sent off as he conceded a penalty, which was scored by Steven Whittaker.
Scott Brown levelled with a curling shot, then Rangers' Steven Naismith got a second caution for simulation.
