To prove it we have to see their next match against Poland and Mexico. I can't imagine Argentina going out in the early stages
Because Poland and Mexico are not easy opponents based on statistics these two countries are stronger than Saudi Arabia.
The victory achieved by Saudi Arabia also gave birth to new history, Saudi Arabia became the first country from the Asian continent to be able to beat Argentina in the World Cup.
I think this is Argentina's defeat that hurts, this will be an important lesson for Argentina, from their first defeat at this year's World Cup, that the opponent that will be faced later is more difficult for Argentina and will meet Mexico and Poland, of course it is not an opponent which is easy for Argentina to face, even though Argentina has an unbeaten track record does not guarantee they will win all matches in the World Cup, because the real matches are in the World Cup, of course all teams will be much different to improve their playing patterns to win important matches, because that would allow that country to qualify for the next phase...