With Cristiano Ronaldo having been controversially sent off in his UEFA Champions League debut for Juventus on Wednesday, a prominent football official has now spoken about why he thinks the Portugal captain was shown the red card.

Click through the gallery above to see pictures of Ronaldo's reaction to being sent off.

After a tussle with Valencia defender Jeison Murillo in the first half of the Biancoeri's 2-0 win over Valencia, the Portuguese received his marching orders, much to his surprise.

A teary-eyed Ronaldo made his way down the tunnel after the referee appeared to believe he had acted in a violent manner during his spat with the Colombian defender.

Former Premier League referee Mark Clattenburg has since given his take on the matter, saying he thinks the additional assistant may have thought Ronaldo used his elbow to hit Murillo in the initial contact.

"With the ball on the left wing, the forward tried to make a run into the penalty area and was blocked off by Jeison Murillo," he told the Daily Mail.

"There was a small push from Ronaldo, which resulted in the Valencia defender falling to the floor, but that was not violent conduct.

"Referee Felix Brych had his back to the incident.

"It was spotted by the additional assistant, standing behind the goal, who may have thought Ronaldo threw an elbow, but that was not the case.

"Ronaldo was then clearly annoyed by Murillo's play-acting and placed a hand on the defender's head.

"The contact looked very slight and I cannot see how the additional assistant, standing some 20 yards away, could deem it violent conduct.

"If I had been officiating this game, I would have given Valencia a free-kick and shown a yellow card to each player.

"Ronaldo will serve a one-match ban, but anything more would be harsh."

Valencia Boss: What Ronaldo Said To Me After Red Card

Ronaldo will now miss Juve's next Champions League match, against Young Boys on 2 October.

Do you think Ronaldo was unfairly sent off? Let us know in the comments section below.