Steven Whittaker picked up two cautions in the first half, before Madjid Bougherra was dismissed deep into injury time and El-Hadji Diouf saw red after the final whistle.

Smith told Sky Sports: "With Steven Whittaker, I wouldn't have argued with the second yellow card but the first one, I felt he was fouled prior to the challenge, so therefore it was harsh.

"Madjid Bougherra's one, he quite clearly wins the ball. I think that one was a complete over-reaction from the referee in the circumstances.

"As far as the last one is concerned, I don't know what happened. That was after the game was finished."

Mark Wilson claimed the only goal of the replay at Parkhead, as Celtic progressed to a meeting with Inverness.

The Hoops also recently triumphed over their Old Firm rivals at the same venue with a 3-0 win in the Clydesdale Bank Premier League.

Smith added: "We never really got going in terms of our overall possession and threat but looked as though we weren't going to lose goals in the manner in which we did a couple of weeks ago.

"Overall, we turned in a better performance than we did recently."

Until recently, Wilson had failed to find the back of the net for Celtic but he has now netted three goals in six games.

He told Sky Sports: "It's unbelievable and it's about time.

"It's something I've always wanted to do for Celtic and then three come along and none more important than that in my opinion.

"I caught it first time pretty well and it was a great clearance off the line.

"I was surprised it came back to me and I didn't catch it at all but I'm happy it bounced over the goalie and in."

He added: "We started the game very well and took the game to Rangers. They tried to sit in and frustrate us.

"When they got the man (Whittaker) sent off it made it a bit easier for us and I was glad to get the goal and get through to the next round."