People mostly see the Saudi pro league as a weak league where players who are due for retirement go and settled I think such mentality shouldn't be considered any more because most teams in Europe also find it difficult to win any team in the Saudi Arabia league, I had full confidence that Real Madrid is going to defeat Al Hilal since they posses more strength and quality players than that of Al Hilal but they disappointed and later settle for a draw.
I think no team or league should be underated as long as football is concerned.
Some teams will certainly be considered to be challengers to strong teams from Europe. Al Hilal is a strong team from Saudi Pro Liga, although there were not many opportunities, but in fact they put pressure and managed to hold Madrid to a 1-1 draw. No matter how they scored, what is certain is that we see the final result in a competition.
Other strong teams, such as Inter and Dortmund, also drew in their first match. There were some surprises, but it probably won't change much for the next matches.