The last time Kylian Mbappe and Erling Haaland shared the same patch of grass on a football pitch the Covid-19 pandemic was only just beginning to run through Europe. Mbappe wore the colours of PSG and Haaland the yellow of Borussia Dortmund and it was supposed to be the start of the rivalry that was football's heir to Lionel Messi vs Cristiano Ronaldo.

A lot has happened since, but somehow, fate hasn't pitted the two biggest names of their generation against each other, until now. At the Etihad on Tuesday, Mbappe will be lining up for Real Madrid having finally moved to the Bernabeu last summer.

The chances of Haaland ever following suit diminished when the Norwegian signed his nine-year contract at the Etihad in January, so the rivalry should remain just that for the long term. This might be the third instalment of their personal battle, but perhaps it is the first of their proper duel for supremacy.

READ MORE: Gonzalez, Ederson, Nunes - Man City injury latest and return dates as Blues handed huge Madrid boost

READ MORE: Pep Guardiola can use Man City gamechanger with unbeaten Real Madrid record - or can he?

Now he's at Madrid, Mbappe will expect to be vying for the Ballon d'Or, an individual award currently residing with Rodri after a night in which City found out just how much stock the La Liga giants put in bringing it back to the Bernabeu. At 26, there is a sense that Mbappe should be making up for lost time having spent too long at PSG.

In the meantime, Haaland has won the Champions League and helped power City to the treble, but he has never scored against Real Madrid. This will be the fifth time he has played against the club that Pep Guardiola refers to as the 'Kings of Europe,' and he has never played an opponent five times or more without scoring against them.

That should worry a Real defence already stripped of most of its defenders. This time, there will be no Antonio Rudiger to try and ruffle Haaland's feathers. Instead, it will be central midfielder Aurelien Tchouameni and rookie defender Raul Asencio who try and stop the Norwegian.

That should give Haaland a boost, and he will be desperate to finally land a blow on Real and perhaps get one over on the forward with who he is surely going to compete for personal records and awards over the next decade, although teammate Ruben Dias insists there is more to the two games than that.

"Personally, I don’t sense any Erling vs Kylian vibes. It’s City against Madrid, there are loads of big names on both sides," he said. "In relation to Erling, he wants to be in this competition and wants to win it just as much as all of it. He will be hungry enough to be there and perform."

There is a point of view that neither Haaland nor Mbappe are having the best of seasons, but their numbers still stand up to scrutiny. If anything, it is a reminder of the sky-high standards they have set themselves in previous years.

Haaland has 25 goals in 33 games, and Mbappe has 22 goals in 34 in his first season at the Bernabeu, and their contributions could be defining in what could well be an open tie.

With Real stripped of defenders and City struggling to control games this season, it could be 180 minutes of chaos. Guardiola's side have been involved in some thrilling, see-saw games of late, and although they don't fit with his desire for stability, they have had to embrace it because they have looked most dangerous in transitions.

Real are likely to field Vinicus Jr., Rodrygo, and Jude Bellingham in addition to Mbappe, and the City manager knows just how difficult it will be to contain that attack in games in Manchester and Madrid.

"It’s impossible to control these four players," he said. "They are exceptional. So how they combine, the runners, the ability one against one, how they keep the ball.

"So all four, they are exceptional. Everybody knows it. So we have to reduce their involvement as much as possible. Knowing that is going to happen, accept it. They have the courage to play.

"To always be present with the ball, it doesn't matter if the opponents are close. They have the ability to keep it and make extra touches and extra passes. And when that happens, of course, they can run, they can combine the shortest passes with the moments in behind.

"So we know it's going to happen. But at the same time, we are going to try to impose our game, to be involved as little as possible with the ball and be smart, especially in the first leg, the way you have to play. It's important to read the tempo, basically, we have to play to get a good result for Bernabeu."

The return of Dias and John Stones to the defence is vital for City if they are to stop Real, but midfield remains a weakness, and if Leyton Orient can run through them and create opportunities, then the likelihood is that Mbappe and Co will be able to do the same. Don't be surprised if this turns into a shootout between Haaland and Mbappe. Many more could follow.