The results are out for their match against Real Madrid, honestly I didn't expect them to be able to produce such a result considering they still had more Real Madrid key players in the line-up. If they can get a result like this against Real Madrid, I think we can expect even better results from them against the other 2 teams, there are still Salzburg & Pachuca.
Al Hilal was underrated because they play in some random SPL. With the look of things, I don't think it's going to be easy with European clubs, there have been some threatening presence performance of these clubs outside Europe. The American clubs and Brazil coming out in good numbers to perform efficiently. Real Madrid become elite and competitive, we know their top goals and they're craving to nail their targets. Al Hilal 1-1 draw with Real Madrid do prove something, they're up and running for the league.
Yes I agree with you, Real Madrid was over estimated whereas Al Hilal was underestimated because they didn't have a squad like Real Madrid or perhaps their status isn't as huge as the Spanish side but at the end of the day the Saudi side proved that they were able to face any challenge that the Spanish side might bring their way. It was world shocking!