Celtic's dreams of a domestic treble remain on course as they progressed on Wednesday to the Scottish Cup quarter-finals with a 1-0 win over nine-man Rangers, who also had El-Hadji Diouf ordered off after the final whistle at Parkhead.
An uneventful match turned ugly just after the half-hour mark when two cautions in eight minutes saw Steven Whittaker sent off sparking trouble on the sidelines with El-Hadji Diouf involved in a confrontation with Celtic manager Neil Lennon. The Hoops made their numerical advantage count in the 48th minute when Mark Wilson scored at the second attempt as Sasa Papac, who had blocked his initial shot, lay on the line.
Madjid Bougherra received his marching orders three minutes into stoppage time after picking up his second yellow while Diouf was shown a straight red for his protestations at the final whistle, in a match where nine players were booked.
The game began at its usual frantic pace and it was the home side that applied the early pressure. Gary Hooper, who grabbed a double in their last meeting, accelerated past Bougherra and David Weir but Richard Foster was there to mop up the danger. Celtic goalkeeper Lukasz Zaluska then gave his defence a scare when he raced out of his box to confront Diouf but Rangers failed to take advantage as his cross was cleared.
The game had been without major incident until Whittaker was sent off in the 36th minute. He collected his first for a foul on Ki Sung-Yeung and after bringing Emilio Izaguirre clattering to the ground referee Calum Murray produced the red. Diouf and Lennon clashed on the sidelines, earning the Senegalese striker a booking.
Celtic were immediately handed a chance when a slack back-pass from Maurice Edu played Giorgios Samaras in but the Greek striker's shot was superbly blocked by the legs of Allan McGregor. Scott Brown, Daniel Majstorovic and John Fleck also found themselves booked before the break.
The Hoops quickly took advantage of their extra man in the second-half as they took just two minutes to take the lead. A ferocious drive from Wilson cannoned off the head of Papac on the line and with the Bosnian international lying on the ground the Celtic defender followed up with a shot that bounced on the turf and high into the net.
Papac was replaced by Gregg Wylde as the Rangers task got even tougher. Ki sent a 30-yard effort just wide before Samaras held off Kyle Bartley to fire a low shot crashing off the base of the post. The Greek squandered another chance soon after when he headed Izaguirre's cross straight into the arms of McGregor as Celtic couldn't add to their precarious lead.
Bougherra, booked earlier for a late challenge on Hooper, picked up his second caution for a foul on Kris Commons three minutes into stoppage time. The final whistle brought confrontation as both benches confronted each other and Diouf was shown a straight red.
More trouble erupted after full time as Lennon and Rangers assistant manager Ally McCoist had to be separated. "I was delighted with the performance of the lads, both footballing-wise and discipline-wise," Celtic coach Alan Thompson said, as Lennon remained in the dressing room. "There is a lot of Old Firm games and we seem to be on a decent run against them."
Rangers manager Walter Smith said: "I don't think we deserved the two sendings off but at least we competed better. We defended well, especially in the first half, but in the second half we were disappointed to lose a goal as early as we did."