Sinfield was sent off in a Super League game against the Tigers in 2015. It was the only time the playmaker was red-carded in his rugby league career.
“Nobody believes me, but I didn’t mean to headbutt him,” he said.
“It was like animals in the wild locking horns when they are in battle or being aggressive to each other; we were having verbals, I thought we were both going to lean in and put our heads together, but he pulled away and I went through with it!
“People want to think for a split second I lost it, but it wasn’t like that at all. It was an accident as much as anything.
“Sinfield admitted the incident came out of frustration at a series of incidents in the match. He recalled: ‘At the start of the game Justin Carney knocked me for six and I hurt my knee. I had to have surgery to get it sorted out in the offseason.
“Late on we were winning by six and in front of their posts. I was screaming at Paulie Aiton to give me the ball, to drop a goal so we’d win the game, but he didn’t hear me, it went to Danny Mags and then Carl Ablett knocked-on off his backside.
“Dorn picked up and made a break and I went in for the tackle. He was holding me down and kicking out, trying to milk a penalty and he kicked me on my bad knee and then in the nuts.
“So in the space of about five seconds I’d gone from a chance of winning the game, to having to make a tackle to stop a break, being penalised and kicked in the knee and the nuts. I got up and I was angry, but I didn’t mean to headbutt him.
“If he hadn’t pulled out I don’t think anything would have come of it. Down to 12 men, Rhinos could not hold out and Tigers hit back to salvage a 24-24 draw. Sinfield was banned for two games and his first match back was the Cup semi-final against Warrington.
“’It isn’t something I am proud of, but I don’t regret it,’ Sinfield said of the red card brandished by referee Ben Thaler. ‘It was another experience. I have experienced most things in the game and that was something new.
“You always learn from any new experience and it probably worked in our favour when the Cup semi and final came around. It gave me a couple of weeks off to rest my sore knee and I went into those games feeling fresh and with even more motivation.”