Celtic manager Brendan Rodgers says he hopes referee Don Robertson can learn from the mistakes he made at Ross County as he heads into the Old Firm derby at Hampden on Sunday.

Robertson, who gave a controversial penalty against Celtic defender Erik Sviatchenko against Ross County, will be an additional assistant to Willie Collum in the Scottish Cup semi-final.

Rodgers revealed he had received a phone call from head of referees John Fleming and says he hopes Robertson will apologise to Sviatchenko when they meet on Sunday.

He said: "Everyone seen the decision last weekend and as a referee especially if you are trying to get yourselves promoted in the game you have to get decisions like that right.

"But we have to try and help the referees we have to try and improve the standard of refereeing, I had a call from John Fleming which I really respected and appreciated.

"Don Robertson doesn't have to ring me or apologies to me, all Don Robertson has to do is make sure he apologises to Erik Sviatchenko but I'm sure he will learn from it.

"But in circumstances like that you have to get that right because if you don't you lose the trust of the players."

Celtic have appealed the decision by Robertson to send off captain Scott Brown, meaning the player is available for selection on Sunday.

Rodgers is adamant it was not a red card offence and says having Brown available for selection is a massive boost to his side.

He said: "It is very important because he is real catalyst for the team, I didn't think he should have been sent off last weekend.

"We have the same referee who made the yellow card decision against Kieran Tierney, so with the consistency with the decision making that's why we are appealing it.

"Of course I am very happy, Scott is a class player and he has been brilliant this season.

"He has played over 50 games for me this season and has been absolutely brilliant.

"I'll repeat I don't think it was a red card. The challenge was aggressive and he may have caught him just above the ankle.

"He has played in countless big games for us under pressure and his temperament this season with me has been absolutely world class."

Rodgers is gearing up for the fifth Old Firm derby of the season, but is confident his players have the focus and the ability to handle big pressure occasions.

He said: "These games no matter what the form was like, no matter how you arrive in the game they are always tough game and the last game at Hampden between the two teams we played very well and came through 1-0.

"My players have been brilliant this season and the odd time they have taken a dip in performance but they have always been able to get a result.

"We are really focused and ready to get a result and perform and that's key.

"The players have shown me enough over the course of the season that at the big pressure games they are able to keep calm, find the control and get the result."