When a football player widely considered to be among the greatest of all time effectively declared war on one of the world’s biggest clubs, the fallout was always going to be colossal.

Over the course of a lengthy interview, Cristiano Ronaldo took aim at Manchester United, the team’s manager, its owners and a succession of former players who he believes have wronged him.

Although the contents of his discussion with Piers Morgan on TalkTV has been the source of countless headlines as it aired over two parts, some of his comments will be of far greater consequence than others.

The Portuguese superstar earns a salary reported to be between £400,000 and £500,000 a week as part of a contract that runs until the end of the season.

At 37 years old, he has been repeatedly excluded from United’s first XI this season under new manager Erik ten Hag – and forced for the first time since he was a teenager to confront the fact he is not an automatic starter for his club.

And whether his second stint at United – which he left for Real Madrid in 2009 – ends as initially intended in May now appears in considerable doubt.

What did Ronaldo say that will be the biggest source of concern to Manchester United?

Probably the most significant sections of the interview centred around Ronaldo’s comments about the club itself, its owners and the manager:

• He accused the club of “betraying” him and claimed he had not been able to help them as he had hoped because it was “hard when they cut your legs”

• The club had made “zero progress” since the retirement of former manager Sir Alex Ferguson, he claimed, while criticising its facilities and adding “the infrastructure is not good”

• Ronaldo criticised Ten Hag, saying “I don’t have respect” for the Dutchman and claiming he had refused to come on as a substitute in a game because he felt “provoked” by the coach

• He alleged that two senior figures at the club doubted his daughter was sick, as he had told them when he missed pre-season training

•The player said the club’s owners, the Glazers, “don’t care about the club, professional sport”

What have United said so far?

Manchester United have said very little to date following the airing of the interview.

The club released a short statement on Friday, saying: “Manchester United has this morning initiated appropriate steps in response to Cristiano Ronaldo’s recent media interview.

“We will not be making further comment until this process reaches its conclusion.”

What legal options do United have – and can they terminate his contract?

There is at least one aspect of the story around which there is seemingly consensus among sports law experts, and that concerns whether Ronaldo’s actions – or words – will amount to a breach of contract.

Udo Onwere is a renowned sports lawyer – himself an ex-professional footballer – who heads the sports practice at law firm Bray & Krais – and represents clients including former United star Rio Ferdinand and current England player Reece James.

“The basic Premier League employment contract means every player is under an obligation that means they’re not allowed to say anything that brings the club into disrepute,” he told Sky News.

“Without a doubt, what he said in the Piers Morgan interview will be an immediate breach. I don’t think there’s really any debate around that, just because of the words he’s used.

“If a player is talking about being betrayed by the club and the club not honouring its commitments to him, then it’s not going to be possible to argue that’s not bringing the club into disrepute.

“The question is whether the club will regard that as being gross misconduct and seek to terminate his contract immediately, or in January when he gets back from the World Cup.

“Alternatively, they may decide to go down the route of launching disciplinary action, and maybe seeking to potentially fine him.”

Jamie Singer, a partner at sports law specialists Onside Law, told Sky News the debate within the sports law industry had largely focused on whether Ronaldo was guilty of gross misconduct.

“When you’re using language like ‘betrayal’ in respect of the club, it’s not going to be hard to demonstrate there’s been a breach of contract,” he said.

“The question is whether it’s so significant a breach that it constitutes gross misconduct.”

Has anything like this happened before?

There are only a handful of cases of relevance in English football.

One high-profile precedent involved Chelsea and former Manchester United striker Romelu Lukaku.

He gave an interview in January, in which he appeared to criticise then-manager Thomas Tuchel – saying he was “not happy” and complaining about the tactics at Chelsea.

In that case, however, Lukaku apologised to the club and was subject to disciplinary action before being loaned to Inter Milan.

“I don’t think anything like that will happen here, given the language that Cristiano used,” Mr Onwere said.

The other key contrast with that case is the fact that Lukaku had only recently been bought for £90m and remained a saleable asset to the club.

“If this was a young Cristiano Ronaldo, and he was worth say £100m or more, they’d probably take a different course of action,” Mr Onwere said.

“But because he is at an age where they couldn’t expect a big transfer fee, and he’s earning £400,000 or £500,000 a week, then they’re more likely to take the view that this has become too much of an expensive headache, and they just need to get rid.”

Mr Singer said the particulars of the case made it a highly unusual one, which would likely have a crucial bearing on the outcome.

“It’s a really intriguing one, because normally clubs steer clear of aiming for termination [of contract] because the value of the player’s registration is so important,” he said.

“But here you could have a situation where both parties would not be unhappy about a termination, and it appears that perhaps Ronaldo may be engineering that.

“From Ten Hag’s perspective, it’s clearly been a thorn in his side… so here we have a 37-year-old who we’re not going to get a big transfer fee for, but who we’re spending an absolute fortune on each week.

“If you compare it to the Lukaku situation, his registration was certainly seen as an asset which you did not want to jeopardise by terminating.

“Ronaldo, however, may actually be seen as a liability rather than an asset.”

Mr Onwere said he had represented one of the few prominent professional footballers to have previously had his contract terminated.

In that instance, the Hull City gave notice they would be terminating Jimmy Bullard’s contract in 2011 following an incident on a pre-season trip to Slovenia – but Mr Onwere said a settlement was eventually agreed after the player appealed.

“This is obviously a very different situation, because here you’re talking about one of the greatest players of all time, someone earning a huge amount of money, but who is 37 years old.”

What course of action are United most likely to take with Ronaldo?

Mr Onwere: “The disciplinary process option might be preferred as they could then manage it within the club, in private, and it would mean they don’t have to air their dirty laundry in public.

“But my gut instinct is that United will want to be seen to deal with this swiftly and very decisively, and I suspect they will seek to terminate [Ronaldo’s contract], just because it has become so public, and they will feel they have strong grounds for doing that.

“They will want to show that they cannot be dominated, even by someone on the level of Cristiano Ronaldo.

“It could be difficult, though, because Ronaldo is a wealthy guy and depending on which course of action they take, there could be pushback, and it could become even messier.”

Mr Singer said Ronaldo could decide to challenge whichever course of action United opted for.

“If he does object, he may choose to defend his position in any internal hearing if the club decide to initiate a disciplinary process,” he said.

“But if the club terminates his contract, he could appeal that to the Premier League and say the club were not entitled to do so and have done so.

“That very rarely happens, because it very rarely gets to the situation where clubs terminate a contract in contested fashion. However, here we are talking about a highly unusual set of circumstances.”

Mr Onwere agreed that the situation was an extraordinary one.

“He’s taken a nuclear option, knowing that it’s going to cause a big hoo-ha, and you’ve got to assume that’s what he wanted,” he said.

“The man that he is, the footballer that he is, has to be respected, and when you’re at that level I can see how he might feel completely disrespected by the club.

“Whether he’s gone about it the right way is a different discussion.

“So I think the most likely situation is that they terminate the contract but agree a settlement of some kind.

“One other option is that they could terminate the contract but hold on to his registration, although that could lead to all kinds of other problems – with him likely arguing that this is a restraint of trade – and they will want to make this as clean as they can.

“The club will be pleased that the World Cup is coming up now, as that will be a welcome distraction that will allow them to get on with things in the background.”