Touts were selling black-market tickets in the winter sun outside the Estadio da Luz here on Thursday lunchtime, and understandably so. The demand is huge.

Portugal face Sweden in the first game of a two-legged tie to decide who plays in next summer’s World Cup in Brazil. It’s a fixture that pits Cristiano Ronaldo against Zlatan Ibrahimovic. Only one can make it to the finals.

Whichever way you couch it, this should be quite a show.

Control: Cristiano Ronaldo (left) does keep-ups in Portugal training with with Helder Postiga watching on

Silky touch: Zlatan Ibrahimovic controls the ball as Sweden prepare to take on Portugal

'Zlatan for me is No 1 in the world,' said Sweden coach Erik Hamren rather boldly here last night.

'He is a world-class player, he is my captain and he is playing for Sweden. I say that he is the very best.’

Meanwhile, Ronaldo’s team-mate Pepe drew his own line in the sand. 'They are two great players, but nothing compares to what Cristiano does,’ said the Real Madrid defender. 'He has unimaginable statistics and is the best in the world. There is no comparison.’

It was tasty stuff ahead of what promises to be an epic tie — the second leg takes place in Stockholm on Tuesday — but the beauty is that none of the talk or the hype matters. The bare facts are, for once, enough because they tell us that one of this much-acclaimed duo will spend next summer on the couch or, at best, the beach.

  
War of words: Portugal defender Pepe (left) and Sweden coach Erik Hamren have differing opinions on the pair

Neither ego will contemplate failure, of course. As such, when that reality lands at one pair of gilded feet next Tuesday in Sweden, we can expect some tears, and then some scattered blame.

Ronaldo is certainly not the best when it comes to accepting his share. Ibrahimovic, meanwhile, doesn’t even understand it as an option. Of the two, though, perhaps Ronaldo owes his country more.

It doesn’t seem like 15 months ago that the former Manchester United star relegated himself to the back of the penalty-taking queue in Donetsk as Portugal sought a way past favourites Spain in the semi-final of Euro 2012. By the time his turn came, the shootout was over.

An act of extreme cowardice or simply a gross miscalculation? Whatever the truth, it was a cock-up of gargantuan proportions and tonight in the city where he made his name it is perhaps time to atone in the only way that really matters.

Payback: Ronaldo, with boss Paulo Bento failed to take a penalty at Euro 2012 against Spain

Weight of a nation: Ibrahimovic frequently carries Sweden's hopes on his shoulders

'He is going through an exceptional moment,’ said his national coach, the rather dour Paulo Bento. 'He is playing the best ever. We count on him, that’s for sure.

'He should have won the Ballon d’Or more times and for his quality and his professionalism he deserves it this year.’

To say Ronaldo brings some form into this fixture is an understatement. The 28-year-old has scored 13 times in his last seven games which, even by his standards of goal-gorging, is rather greedy.

Ibrahimovic, though, is only a goal behind over the same stretch. Between them they have a goals record this season that your average Barclays Premier League club would find acceptable.

'Of course, it’s a fight between these two world-class players,’ added Sweden’s Hamren. 'Zlatan needs support but if he gets that from the team then he can be the match-winner.

  
Adulation: Both Ronaldo (left) and Ibrahimovic come into the crunch clash in good form for their clubs

'It is the same for Portugal. Ronaldo is important for them. He is a really big star. He is the world-class player in their team but they have 10 other players.

'Zlatan has been scoring well recently, so that’s good. But so has Ronaldo, so maybe their form is pretty even.’

Logically, neither of these teams should trouble the scorers in Brazil next summer. Portugal, for example, failed to beat Israel home or away in finishing second in their qualifying group while Sweden have a habit of narrow, honest failure at major tournaments.

Wide open: But who will face a devastating summer of missing out on the World Cup?

Nevertheless, the disappointment felt by a global public at the absence of Ronaldo or Ibrahimovic will be keen.

It will be a while since a World Cup has taken place in the absence of one of the game’s  genuine superstars.

We will cope, of course. The greatest show on earth will roll on. Whether the two men concerned will manage is another matter entirely.

Watching your rivals play in a World Cup without you is akin  to watching your favourite girl stepping out on the dancefloor with someone else. How does a man deal with that?