Stop me if you have heard this one before. Cristiano Ronaldo wants to leave Real Madrid.

He was so determined to get there in 2008, and when he succeeded in 2009 that it is curious why almost every year stories appear in the summer that he wants to leave.

In 2012, it was down to being loved, or unloved as the case may be, and apparently, that was a close call as he did appear to be serious about wanting away. Yet as has been the case since then, Madrid went over backwards to try and appease him. And he stayed.

He is often asked about his time at Old Trafford, and he has never hid his affection for the club. He cites his education at Manchester United as being the reason he is the player he is. Normally, that is enough to spark rumours.

Spanish authorities have angered Ronaldo

This time it is slightly different. He is being accused by the Spanish tax authorities, of deceiving them over his income. In similar circumstances to recent cases involving Lionel Messi and Javier Mascherano, he faces paying a huge fine or potentially jail.

The issue surrounds his image rights and earnings outside of Spain. He is described as 'upset' over his prosecution, because he wanted to avoid this situation. He engaged with the authorities and allegedly paid a large sum, and the fact he had co-operated has left him incandescent.

So he is not upset at Madrid, and he is not pining for another team. This time it could be serious.

When Madrid signed Gareth Bale he overtook Ronaldo as the world's most expensive footballer. Paul Pogba's transfer to United leaves Ronaldo in third. It wouldn't have been lost on him that if he does move, he will regain the tag and then some.

Huge sums needed

He has a €1billion buyout clause in his current contract. That is as stupid as it sounds, and was probably only inserted to massage Ronaldo's ego. It would still take some serious cash to prize him away.

The figure that is being spoken about if a transfer were to transpire is in the region of €150m (£131m). That is eye watering. Ronaldo is 32, not 22.

Manchester United could afford this, and his enormous wages to boot. So is this a real prospect if Ronaldo is deadly serious?

Signing Ronaldo would be a coup despite his age. Zlatan Ibrahimovic showed last year that age is just a number, but with Ibrahimovic's future almost certain to be away from Old Trafford, then Ronaldo would be some replacement.

It would scupper any deal that is being brokered for Alvaro Morato or Andrea Belotti. Both players look like they could be brilliant acquisitions, and long term prospects. Ronaldo can score as many as both of them put together though.

Goals guaranteed

If you need an injection of goals, then passing up on the chance of Ronaldo doesn't seem like the most sensible way of going about it. Alan Shearer and Ruud van Nistelrooy were fantastic goal poachers. Ronaldo surpasses both and brings the star quality and skills on top.

The money is a concern, although the way United have spent in the post-Ferguson years, it appears to be no object. It would not be like the Pogba deal, though. Adidas would certainly not be laying their weight to push a deal through.

United would recoup some of the outlay with sponsorship deals and the like, but his age means they would not have long to capitalise.

Will Ronaldo go? Probably not? If he did, would United take him? They would be mad not to, but they would be putting almost all their eggs into one basket. There are other transfer targets, and having already spent over £30m on Victor Lindelöf then it wouldn't leave much left for the remaining jigsaw pieces.

This long-running soap opera is not finished yet, and almost has more legs than the David De Gea equivalent. Does it end this summer? Watch this space.