Both Cristiano Ronaldo and Luka Modric can be considered the exemplars for their respective sides, despite the fact that the Portuguese is already 41 years of age and the Croatian a slightly younger but no less sprightly 40.
Can Ronaldo do something he has never done before against Croatia?
In what could well be the final World Cup appearance for either, the former Real Madrid teammates will give it everything to make it into the Round of 16, although Ronaldo will need to do something he's never done before - score a World Cup goal in the knockout stages - if he is to be of service.
He did score twice in the group stages against Uzbekistan, but failed to find the net against DR Congo and Colombia.
With respect, Croatia, for whom Modric will be making his 23rd WC appearance, are likely to prove Portugal's toughest test in the tournament so far, making any Ronaldo goal at this stage a potentially important one.
That double was enough to see Cristiano take the mantle from Eusebio as Portugal's all-time top scorer in World Cup history with 10 goals in his 24 matches, though Eusebio's total of nine came in just six games.
Vitinha the key
In his eight previous WC knockout games, Ronaldo has had 29 shots without finding the net, which is the joint-most efforts without scoring (with Brazil's Roberto Carlos) since 1966.
Portugal remains unbeaten at this World Cup, however, and were they to beat Croatia, it would be only the third time - 1966 and 2006 were the others - that they have been unbeaten in four matches at WC tournaments.
They need to up their intensity in order to do just that, given that during the group stage, though they had their highest average possession at a WC (62.5%) and completed their most passes ever (1,690), their total of 37 shots (12 on target) is their worst at the tournament apart from in 2018 (32 and nine respectively).
If the Portuguese are going to progress, then how influential Vitinha is will determine how far they go.
With 54 completed passes against Colombia (100% accuracy), he earned the accolade of the joint-most passes on record by a midfielder in a World Cup, whilst his 270 passes in the group stage are the most on record by any Portuguese player.
Furthermore, he is the metronome by which the entire way Portugal plays is set.
Weight of history against Croatia
Croatia will be determined to keep up their record of progressing past the first knockout round of a World Cup, something they managed to do on all three previous occasions (1998, 2018 and 2022).
Were they to emerge victorious, it would also be the first time since the 2018 World Cup that the Croats have won three successive major tournament matches.
It's clearly going to be a tough ask for Modric and Co., however, as they've only won one of their 10 previous meetings, drawing two and losing seven, and Portugal haven't lost in the six competitive meetings between them (won five, drawn one).
Although Ronaldo has hinted that he could still play in the 2030 World Cup in Saudi Arabia, where he currently plays his club football, he will be 45 by then and, realistically, the Portuguese football federation will have other options available to them.
Attacking formations promise goals
In what could therefore be his 25th and final appearance for his country at the World Cup - only Lionel Messi (29) has more - there's some certainty to Roberto Martinez's team going all out to extend their stay in the United States for at least one more game.
With both sides expected to employ a 4-2-3-1 formation, we could witness one of the games of the tournament, too.
Nuno Mendes and Joao Cancelo will raid down the flanks for Portugal, with Pedro Neto and Joao Felix providing ample support in attack for the main man, Ronaldo.
Not forgetting the creative play from both Vitinha and Bruno Fernandes in midfield, where Mateo Kovacic and Modric will provide a double pivot in front of the Croatian back line to try and frustrate Portugal, and curtail their attacking intent.
Ivan Perisic's deliveries remain some of the best at the tournament, so if Ante Budimir can escape the shackles and use his physical prowess to torment Ruben Dias and Renato Veiga, there's every possibility for Croatia to get their noses in front.
Martin Baturina showed what he's capable of against England, and his late arrivals into the Portuguese box could be Zlatko Dalic's secret weapon, whilst Petar Sucic's role in behind Budimir is also vital to Croatian aspirations, as his first-class movement could be the door opener for the underdogs.
Follow Portugal v Croatia with Flashscore.
Watch the World Cup 2026 live on ITVX via Prime Video here - live coverage, highlights, and analysis.
