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Some players are good at hiding their true feelings. They recognise and keep in mind the cameras trained on them at all times, maintaining their poker faces as so many look for any hint of a reaction. Cristiano Ronaldo is not one of those players.

Hooked for tactical reasons for possibly the first time in his Real Madrid career in the club's 2-2 draw with Las Palmas on Saturday, Ronaldo looked towards the bench in bemusement. He rolled his eyes and upturned one corner of his mouth, expressing his disgust at the decision made by Zinedine Zidane. For so long untouchable as the club’s ultimate Galactico, he had now been brought back down to earth.

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Reports have since surfaced of a dressing room rift between the Real Madrid manager and No. 7, with one newspaper claiming Ronaldo insulted Zidane’s mother in a barrage of post-match abuse, as per SPORT. The Portuguese winger has long been known as a bad loser, but it would seem he’s an even worse substitute.

So, is the age of Ronaldo over at Real Madrid? Is this the beginning of the end for one of the sport’s greatest players? At 31 years old he is now entering the twilight of his career, even if he can reasonably claim to have a number of years left in the tank, but was Zidane’s withdrawal of Ronaldo against Las Palmas an indication of how life will be for the winger from now on?

Zidane has insisted all is well between himself and Ronaldo ahead of Tuesday’s Champions League group game in Dortmund. "Not only Ronaldo gets upset when he is substituted," he said, as per AFP (h/t Yahoo). "Everyone does. Everything is normal, everything is good. We have to live with the discussions. I'm not stupid, he's not stupid. We have travelled here with just one goal and we're thinking only about the game.”

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Nonetheless, Saturday’s episode in Las Palmas raises a compelling discussion over Ronaldo’s place at the Santiago Bernabeu. Injuries have taken their toll on him over the past few seasons with the winger now in undeniable decline. He’s not the player he was even a year ago, and Zidane has surely recognised that.

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Of course, Ronaldo is still much better than he has shown so far this season. His lack of a pre-season has had an impact, with the 31-year-old still carrying the injury he picked up in the European Championship final for Portugal against France. Zidane was possibly protecting the player by taking him off on Saturday, not that Ronaldo saw it that way.

As one part of the so-called BBC, Ronaldo, along with Gareth Bale and Karim Benzema, has come to define the current era of success at Real Madrid. The trio have fired the club to two Champions League titles in the past three years, with Ronaldo the face of glittering achievement in the Spanish capital.

That is in the process of changing, though. With every passing game it’s Bale who takes on the mantle as the figurehead of Real Madrid’s front line. Without the Welsh winger Zidane’s side lacks drive and energy. He too has endured a fragmented start to the season following the European Championship, but he has been notable in his absence on the occasions he has been forced to watch from the touchline. More so than Ronaldo.

Indeed, if there was once a dressing-room power struggle between Bale and Ronaldo, the Welshman is starting to pull clear of the three-time Ballon d’Or winner. It could be argued that Bale is Real Madrid’s most important attacking player, not Ronaldo. If Zidane had to choose one over the other the unfortunate truth might become apparent to the Portuguese.

For the moment, though, Zidane must find a way to accommodate Ronaldo in his first-team fold. While the likes of Marco Asensio and Lucas Vazquez have made a strong impression this season, holding their own in the Real Madrid first team, it could never be argued that Ronaldo, at his best, doesn’t warrant a place in the lineup.

But Zidane must be careful in dealing with a delicate character at a crucial juncture of his career. Ronaldo showed against Las Palmas that he doesn’t take too well to anything that could be perceived as public indignation.

"Nothing has changed. All this talk [about the incident], more than about tomorrow's game, well we must live with that. We are relaxed. I'm not stupid, and he is intelligent. We are all here for the same thing,” Zidane continued when asked earlier this week about the relationship between himself and Ronaldo, per Dermot Corrigan of ESPN FC.

Tuesday night’s game against Borussia Dortmund will offer some sort of gauge as to whether Zidane is telling the whole story, assuming Ronaldo is fit enough to feature. The Real Madrid No. 7 will also have the opportunity to prove that he is big enough to accept where he is in his career and that his place in the starting lineup is no longer guaranteed.

Real Madrid might have kept a largely settled squad over the summer for the first time in years, but the club is currently in transition. Ronaldo has come to define the Santiago Bernabeu outfit over the past seven years, with the Portuguese winger the face of the club’s second coming of the Galacticos ethos.

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But Zidane, along with Florentino Perez, must now consider drawing up an exit route for Ronaldo. It seems unlikely that he will ever accept a role on the sidelines as a fringe player, and so his place at Real Madrid could quickly become unfeasible.

Ronaldo has spoken recently about his desire to retire in the Spanish capital, per Jugones (h/t MailOnline). However, such remarks might be made on the assumption he will start as long as he is a Real Madrid player. There will come a time when that is no longer a reasonable assumption.

The age of Ronaldo has been a shimmering one. He might well go down as the greatest player in Real Madrid history, which is no mean feat given the stature of the club and the superstars who have pulled on the famous white shirt over the years. But all good things must come to an end, they say, even if they are the best there has ever been.