Spain and Portugal are the favourites to progress from Group B considering they have a substantially better pedigree than their group rivals Iran and Morocco. As their Round of 16 opponents will come from a below-par Group A, there is a sense that this match - likely to determine final group position - will be of little significance in their overall tournament finish.
Yet this is still a World Cup match between two nations that have a long rivalry, not least because they border each other. National pride is at stake and you would expect to see the strongest lineups possible when this one gets underway. There is also a feeling that there has been a shift of power now that the Portuguese hold the European Championship trophy, a title that only recently belonged to Spain.
This leaves us with a match that will be one of the best in the group stages. Both sides have a wealth of superstar players to call upon - Spain have arguably the best goalkeeper on the planet in David de Gea, while Portugal boast one of the best outfield players in the world in Cristiano Ronaldo. This is a clash between two teams that are capable of winning the tournament.
So how do we split them? Although Portugal look stronger now than they did when they won the 2016 European Championship, they may be lacking pace defensively with the likes of Pepe, Jose Fonte and Bruno Alves all in their mid-thirties. We saw how strong Spain can be in attack during the qualifiers, and the addition of Isco has us thinking they can turn back the clock to 2010 and win the tournament.
Spain haven't started strongly in the last two World Cups, while Portugal were average in the beginning at the 2016 Euros. This will all be about which team can hold their nerve on the big stage and we are leaning towards Spain, who boast a stronger side on paper.
The top betting sites agree, and have listed Spain at around -113 to win this match. We believe the draw is also a good option at +246, while the +317 available for Portugal is excellent value considering they are the European champions and will feature Ronaldo.
We'd like to believe this one will feature goals from both sides as each contain excellent attacking rosters. 2-1 to Spain is our pick.