Round one

Keane is in peak sullen punditry mode. Slouched in his chair, he has the air of a man who would rather be tucking into a cup of tea and a Starbar at a motorway service station on his way back home. He is almost daring Sky Sports presenter Dave Jones to ask him a question. Go on Dave, give it a go. Take him on. Get this thing started.

Dave Jones: “What should [the manager] do with Ronaldo?”

Roy Keane: “Play him.”

Dave Jones: “Start him?”

Roy Keane: “You have to. Ronaldo came off the bench – Ronaldo isn’t one for coming off the bench – he was probably freezing there. Ronaldo has not come back to Manchester United to sit on the bench.

“Why Carrick is trying to give him a high-five, I don’t know. Let him get down the tunnel, there is nothing wrong with a player being upset. Ronaldo has not come back to Manchester United to sit on the bench. What is the point?

“He is a world-class player. His stats since he came back to the club are ok – he has got some goals and some assists. This idea that Ronaldo is going to start closing people down? He’s not. Sometimes you have to work around a superstar. I’ve played with players who don’t do the bit you hope – the Cantonas of this world – but you forgive them because they score the winning goals in tight matches.

“Ronaldo has to be in the starting XI. This idea of resting him? Villarreal didn’t take a lot out of the players and they are not playing again until Thursday night. He could have played today easily.”

Verdict: Even Keane’s biggest adversaries will have raised a smile at the deftness of his initial two-word answer. He has not traveled down from Manchester for stupid questions. At the second time of asking, Jones elicits the response he was after with Keane laying out his argument without any need for overexertion. A gentle start to the heavyweight battle to come.

Round two

Now it is time for Carragher to have his say. A consummate professional until fully riled up, the former Liverpool man is alert, sitting upright in his chair with hands gently clasped together on his lap. He does not agree with Keane, but has no desire to be dragged into anything unsavoury.

Dave Jones: “Do you think [Ralf] Rangnick will see it like that?”

Jamie Carragher: “No. I think Rangnick will not cause himself a problem initially coming into the club and putting Cristiano Ronaldo on the bench, but I think this idea that Cristiano Ronaldo has to start every game and play every minute of every game I don’t think is right.

“Going away in big games I can understand why Michael Carrick never started him against Chelsea.

“You saw when Ole Gunnar Solskjaer brought him off in Switzerland in an early group game, they were down to 10 men in the game, they brought him off and they lost the game because of a Jesse Lingard bad back pass.

“There was this big story that he brought Ronaldo off. He’s 36. He then didn’t start him against Everton and Ronaldo walked down the tunnel.

“Now, Ronaldo’s not the player he was. He’s still obviously delivering for Man Utd in terms of goals, but I don’t think it should be a big story if Ronaldo doesn’t start every game or at times comes off in a game of football.”

Roy Keane: “Not every game, Jamie, but this is a big game for Manchester United. I’d forgive some of the group games in the Champions League when you’re thinking Man Utd are still going to get through, I understand that… but Ronaldo, if you bumped into him in the car park, you see a guy who has won everything in the game and who has come back to United to try to lift the club. Of course he will want to play in these games.”

Jamie Carragher: “That’s every player when we are playing the game.”

Roy Keane: “But they are not all world class! They won’t have had 800 games in their career! If you were watching today and Man Utd were poor but Ronaldo is on the pitch you are still thinking: ‘Well if the ball falls to anyone in world football, even at 36, it’s Ronaldo’.

“It’s not like he has come back to the club and not scored and you go: ‘He can’t get up to speed, he looks awful, he’s not up to speed’. He’s on it. He looks interested.

“And this idea that he then gets the blame for the high press…”

Jamie Carragher: “He doesn’t press, does he?”

Roy Keane: “He’s not pressed for four, five, six years! I said when he came back that he wasn’t going to fix Manchester United’s problems. But you do not bring Ronaldo back to Man Utd to sit on the bench.

“Of course he is not going to start every game. But it’s Chelsea away where it is going to be counter-attack and you might get one or two balls into the box, and you want to drop Cristiano Ronaldo?”

Verdict: Something is brewing here. The voices are starting to shift up a few notches and Keane is forced to ditch his languid pose. A fundamental difference of opinions has emerged where Keane is effectively willing to give Ronaldo special dispensation because he is (or perhaps was) one of the greatest footballers in history, but Carragher does not feel he deserves it. After the exploratory jabs to kick off this encounter, hands are starting to be thrown, with Carragher content to let Keane do the heavy lifting before cheekily landing a couple of swift upper cuts.

Round three

It turns out there is a third pundit in the studio. Jimmy Floyd Hasselbaink is one of those nice footballing chaps who few people have strong feelings about either way. But he is not cut out for this. His foolish attempt to interject is routinely ignored with total disdain by our two protagonists. Stay out of it, fella. This is big-boy stuff.

Jimmy Floyd Hasselbaink: “The thing is, does he have to press? Do you have to be successful for Ronaldo to press? Exactly, so you need to find a way to get Ronaldo on the pitch and…”

Roy Keane: “Do you think Rashford pressed today?”

Jamie Carragher: “Why did Manchester United sign Ronaldo in the summer? They signed him because they were terrified he was going to go to Man City. That’s why they signed him.

“There was no plan to sign Cristiano Ronaldo. They signed him at the last minute because he was going to go to Man City.”

Roy Keane: “But he was always going to play, Jamie. What, they were going to sign him just to not go to City but come and sit with us on the bench?”

Jamie Carragher: “I didn’t say that. I’m saying is a Manchester United manager not allowed to put Ronaldo on the bench? They’ve come here to Stamford Bridge and the guy that’s played has scored the goal.”

Roy Keane: “Of course he is. Stats have taken over the world so show me his stats. His stats since coming back to Manchester United are good…”

Jamie Carragher: “Goal scoring-wise, yes. Definitely.”

Roy Keane: “What’s the game about? You talk about [Mo] Salah. The game is about goals, Jamie.”

Jamie Carragher: “Where are Manchester United in the league? Are United any closer to winning the Premier League? That’s what he’s been brought back for.”

Roy Keane: “The game is about goals, Jamie! What did Ian Rush do? He scored goals!”

Jamie Carragher: “Did he press as well? Ronaldo doesn’t.”

Roy Keane: “He did, but he didn’t score as many as Ronaldo.”

Verdict: The crowd are on their feet here, cheering as a crescendo is rapidly reached with both men unleashing and matching each other blow for blow. There is no time for a reasoned argument here. Bang! Keane lands what he thinks could be the pre-cursor to an early knock-out with a vicious straight right about Ronaldo’s goals. Bang! Carragher responds with a left hook by mentioning United’s league position. Bang! Keane, ever the street-fighter, delivers a borderline low blow to the gut with mention of Salah and Rush. If he can get Carragher firing on emotion, he has him right where he wants him.

Round four

Carragher can spot the danger here. He does not want a close-up exchange. He is a calm mover, who excels at biding his time and gently making his point with well-researched arguments. Nothing good can come from being dragged into one of Keane’s brawls, so he attempts to bring things back down a level. Play your own game, Jamie.

Jamie Carragher: “I’m not criticising Ronaldo as a player. What can he do at [36]? He’s a phenomenon in terms of goals but I mentioned this in midweek with Lionel Messi. PSG have signed Messi. Man Utd have signed Ronaldo. They are two of the greatest players of this generation. Yes, two of the greatest players of all time.

“Are Man Utd closer to the league title right now than they were last season? No. Are PSG closer to the Champions League with Messi in the team? No. We talk about goalscorers or whatever position you are, you bring your own input to the game, but football is a team game.”

Dave Jones: “So you think signing Ronaldo was a mistake?”

Roy Keane: “Ronaldo was never going to get Man Utd back winning league titles.”

Jamie Carragher: “What was the point in signing him? He’s [36].”

Roy Keane: “To win trophies! It’s about trophies. Did you win the FA Cup?”

Jamie Carragher: “Yeah, I did.”

Roy Keane: “He has come back for the FA Cup and to get in the Champions League! They have got through to the next round of the Champions League. How much do you think that is worth to the club when you are looking at the business side of it – the Glazers, the share price? That’s what he has come back for.”

Jamie Carragher: “If you finish second last year…”

Roy Keane: “Second is no good to you…”

Jamie Carragher: “I know! And then you sign Ronaldo at [36]. You are not going to win the league in four years. If you sign someone at 36 or 37, it is to win right now. If you sign Raphael Varane, a four-time Champions League winner and a World Cup winner, it’s to win right now.”

Verdict: Carragher cannot resist. At the first sign of a Keane interjection, the pre-encounter tactics go out of the window. A brutal fight has emerged and both men are now attempting knock-out blow after knock-out blow. Carragher can sense weakness in Keane’s argument that Ronaldo returned to Old Trafford to win the FA Cup. He is emboldened. Has Keane allowed an opening to give his rival the upper hand?