Rangers manager Steven Gerrard has insisted that referee Willie Collum got the big decision wrong as Celtic won 1-0 in the Old Firm derby on Sunday.

Olivier Ntcham scored the only goal of the game, finishing off an incisive counter-attack, but there was controversy at the start of the break when Rangers midfielder Ryan Jack went down under pressure from Tom Rogic.

Rogic took control and began the move that led to the goal but Gerrard was adamant that he should have been penalised. He said that Collum had not only missed the foul but had dismissed communication from his fourth official,

"For me, it's a foul," the Rangers boss said. "And it's also a foul for the fourth official who is shouting down his mic 'Foul, foul, foul'

"The referee in the middle has ignored that advice but for me it's a blatant foul. He's sweeped his legs .

"Jack did well to get himself between the man and the ball and for me it's a clear foul."

Gerrard revealed that he had spoken to Collum after the final whistle and the referee had stood by his call.

"He disagreed and he doesn't think it's a foul," the manager said.

"I think when he sees it, he hadn't seen the incident, when he sees it again I think he'll change his mind because for me it's a blatant foul.

"I've seen it again. Five times. For me it's a foul."

The Rangers boss also conceded that his side had a major decision in their favour, with goalkeeper Allan McGregor not penalised for an apparent kick at Kristoffer Ajer. The incident wasn't spotted by Collum or his assistants but Gerrard said it was a red card offence.

"I think he has lashed out," he said. "Of course I will speak to him.

"I am honest. I will tell you what I see. If something is blatant it is blatant."