Cristiano Ronaldo's Champions League debut for Juventus did not go to plan.The Italians go into the competition as one of the favourites with the 33-year-old expected to fire them to glory.They opened their campaign against Valencia, but while they would end the game with a victory, Ronaldo's night ended in despair.The Portuguese striker was involved in an altercation with Jeison Murillo.Ronaldo placed a hand on his opponent's head after the two collided in the box; an action the referee deemed as violent conduct.Ronaldo was evidently furious and left the pitch in tears and, to be honest, he probably had reason to be upset.If you haven't seen the incident, watch it below:

The incident has proven very controversial with many big names weighing in on the debate.

A report from Marca has described how Juventus players have reacted to the incident - and they write that some of his teammates have a very interesting theory for why he was shown red.

"The send-off in Juventus' debut Champions League match this season has brought some suspicions to the Juventus players, who have yet to understand the referee's decision," Marca write.

"Some of his teammates believe it is revenge by UEFA for his absence at the gala in Monaco."

That's very interesting indeed.

It has been well documented that Ronaldo failed to attend UEFA's Player of the Year awards last month after knowing he had not won the top prize.

His teammates think that the red card was in fact pay-back from UEFA for his no-show in Monaco.

Alex Sandro has said that Ronaldo is 'fired up' following the incident.

"Cristiano looks really fired up," Sandro told Sky Sport Italia, per the Evening Standard.

"He's a highly experienced player and he knows that what happened in Spain is in the past now. He's already looking forward.

"Cristiano has brought lots of qualities to the team. I'm getting to know him, learning the sort of runs he makes and how he likes to receive the ball.

"I think in time I'll be able to provide him with a fair few assists."