In perhaps the biggest matchup of the tournament so far, Group H winners Spain face Portugal in the Round of 16 on Monday evening in Dallas, Texas, USA. Both sides are ranked in the world's top five national teams according to FIFA and have the capabilities to make this match a World Cup classic. 

The biggest talking point heading into this game is, of course, Cristiano Ronaldo. At 41 years of age, the five-time Ballon d'Or winner is captaining his country in what has been confirmed to be his sixth and final World Cup tournament. Ronaldo has scored three goals in four matches so far in this campaign and is set to start up front against the European champions.

Spain head into the match as favourites after their demolition of Austria in the Round of 32. La Roja were very impressive throughout the 90 minutes and eased to a 3-0 victory over Ralf Rangnick's side. Spain are also yet to concede a goal at this tournament and are many people's pick to lift the trophy in a few weeks time.

It is Lamine Yamal against Cristiano Ronaldo for a place in the quarter-finals, where the victors will face either Belgium or the USA. Spain are hoping to make another huge statement by knocking out their near neighbours, whilst Portugal are hoping for one last miracle from their greatest ever player as they look to close his stellar career with the one trophy he craves.

In their last match, Portugal defeated Croatia in dramatic fashion as they came back from 1-0 down. Cristiano Ronaldo equalised for Portugal from the spot 15 minutes after Ivan Perisic's opener. Substitute Goncalo Ramos then scored a brilliant header to win the match in stoppage time. As well as this, lots of VAR controversy went in Portugal's favour, breaking Croatian hearts. Josko Gvardiol thought he had levelled the match after 10 minutes of added time but his goal was ruled out due to an offside in the build-up.

Four goals were ruled out by VAR throughout the match, including a Ronaldo beauty and three Croatian goals. This win was Portugal's second of the campaign, with their other two fixtures resulting in draws to DR Congo and Colombia. Roberto Martinez's side finished second in their group behind Colombia but will be hoping they can find momentum at this crucial point.

Spain's tournament started underwhelmingly when they drew 0-0 in their opening match against Cape Verde. That result now looks understandable considering the results the African islanders earned during their debut run, but La Roja have since won all three matches and are yet to concede a single goal.

Luis de la Fuente's team cruised past Austria, beating them 3-0 and showing why they have been dubbed as one of the favourites. Mikel Oyarzabal scored another brace to take his total up to four so far, and Pedro Porro got his first international goal for Spain.

Although Austria were not at their best, Spain put on a dominant performance in Los Angeles. Their biggest threats are 18-year-old Lamine Yamal, who Portugal will be hoping Nuno Mendes can keep quiet, and their elite midfielders, like Pedri, Rodri and Fabian Ruiz.

No injuries have been reported for either side ahead of the match as of yet. Nico Williams and Yeremy Pino both missed Spain's last match due to injury but their availability has not been fully confirmed by Spain's manager. Nico Williams is set to make the bench and could feature depending on the situation, but de la Fuente has insisted they should be careful with him when he spoke to the press yesterday.

"We’ll see how the game develops. That will tell us whether he gets minutes or not. We’ll do what’s best for both the team and for him. He could play despite the limitations of coming back from injury and a layoff, but it’s very different coming into a game when you’re comfortably ahead than when you’re chasing it. We’ll see."

The midfield for Spain has changed each time they have lined up for their four matches. Dani Olmo has started twice, including in the last match, but Fabian Ruiz and Mikel Merino have both been brought in for the other two games. 

Spain's front three will stay the same, with Alex Baena, Oyarzabal and Yamal, but the defence could be altered to nullify Portugal's attacking threats. Rafael Leao will surely start after an outstanding performance in the last match, so de la Fuente will have to choose between Porro and Marcos Llorente to stop him.

Ronaldo will lead the line and captain his country once again for potentially the last time. The 41-year-old confirmed this tournament will be his last World Cup, which makes it even more special for the fans. Ramos has shown how impactful he can be from the bench so Martinez is expected to utilise him later on.

Portugal could set up more defensively to hit try to hit Spain on the counter against their high line. Leao and Pedro Neto are most likely to start out wide and Bruno Fernandes will accompany the PSG double-act of Joao Neves and Vitinha in midfield. 

Spain could dominate possession but they must be careful of Portugal's pace on the break. The matchup between Mendes and Yamal is the biggest on the pitch and has served up some entertaining battles in the past. Whoever wins that one will be vital as both sides hope to reach the quarter-finals. 

Portugal 1-1 Spain (Portugal win on penalties)

Spain will control most of the possession, although Portugal will have their moments, but Martinez's side will have to use their pace in wide areas to cause La Roja problems. Leao was outstanding against Croatia and if he can replicate that kind of performance, he will cause any right-back huge issues. However, he will also have to track back to help Mendes out against Yamal, which every team has tried to do so far against the young superstar. 

Ronaldo may not be the player he once was but he has proved he can still score goals at this level. It is hard to see him having a major impact on this match but his job will be to occupy the two centre-backs of Spain to allow for his team to attack efficiently.

I think this match could be a close one and it could suit Portugal more. Spain struggled to break down Cape Verde in their first match and have seemed to struggle more against low blocks compared to when the game is more open, like against Austria.

If Portugal set up deep and hit them on the counter, they could stay in the game and create chances to score. They will not have as many chances as Spain but I think they could make it difficult for the European champions.

I think this one will go the distance and I think Portugal will edge it on penalties. It largely depends on which version of these sides turn up, because Spain have shown how devastating they can be in attack. But Portugal have started to find a way and I think it could be similar to their match against Croatia. Will Portugal pull off an upset or will Spain make a major statement?