Celtic manager Neil Lennon thinks that clashes between rivals in Old Firm derbies are acceptable as long as they do not 'spill into something outrageous' ahead of the renewal of acquaintances between Scott Brown and El-Hadji Diouf.
Hoops captain Brown and Rangers forward Diouf traded insults during and for several days after the 2-2 Scottish Cup draw at Ibrox earlier in February.
Brown received a yellow card for celebrating in Diouf's face after netting Celtic's second equaliser, but he went on to describe it as 'the best booking I have ever had'.
The Senegalese player faces a hostile reception at Parkhead on Sunday, having spat on a Celtic fan while playing there for Liverpool in a Uefa Cup tie in 2003.
Lennon was keen to play down the feud between the two players ahead of Sunday's Scottish Premier League clash, but he also said: "Every Old Firm game is different.
"Both teams have their own personalities and sometimes it can get a bit feisty but there is nothing wrong with that, as long as it doesn't spill into something outrageous.
"Basically you want to keep 11 players on the pitch.
"Each game has its own personalities. It might be two different players you are talking about after Sunday's game."
Celtic are perceived to have an advantage given that Rangers played against Sporting Lisbon on Thursday night while the team from the east end of Glasgow had a free week.
But Lennon is not sure that extra match will hamper Rangers, as he said: "When I played you just wanted to play games - you didn't have to do much training in between.
"Maybe we might be a bit fresher, I don't know. Maybe the extra game will do Rangers the world of good. We will have to wait to see what happens on Sunday."