Rangers legend Ally McCoist went head-to-head with Celtic icon Chris Sutton as they debated the weaknesses in their former sides ahead of Sunday's clash.
Neil Lennon 's side currently hold a five point lead at the top of the Scottish Premiership, though their city rivals still have a game in hand.
They meet at Celtic Park this weekend, and on BT Sport 's Scottish Football Extra, host Darrell Currie asked whether Olivier Ntcham should continue in his role behind Odsonne Edouard.
Sutton responded: "I don't know, because I don't think Celtic are getting the best out of Ryan Christie.
"That's an interesting one. James Forrest is more effective off the right-hand side.
"You'll throw at me: 'well he scored against St Mirren and had a strong game'.
"I think he was man of the match but that was decided by Alex Rae and Jackie McNamara...
"Having said that, he played very well.
"I think Tavernier is the weak link - or one of the weak links - at the back for Rangers, so I'd like to see Mikey Johnston up against him."
Rangers legend McCoist hit back though by pinpointing what he saw as a weakness in the Celtic defence.
He responded: "How are Celtic defensively? In the middle of defence?"
Host Currie noted that Jullien had been described by Sutton as being "a bit shaky" during the win over St Mirren.
McCoist continued: "That's the reason I'm asking that."
Sutton had to concede that his fellow pundit had a point.
He said: "That was an interesting one, because we saw him get a bit emotional like he did against Livingston earlier on this season.
"But Jullien against Morelos - so far this season Jullien has got the better of him.
"I've talked about Jullien being emotional: can Morelos keep his head in a big derby game? I'm not so sure he can."
