As you said above, Al Ahli actually did not experience a decline in performance, but Al Ahli previous defeat when facing Al Fateh could have been predicted before the match started. Regarding the Al Nassr match that will face Al Ahli, it is actually too early because currently Ronaldo is playing for his country and it is uncertain whether he will appear in the match against Al Ahli later. If in the upcoming match Ronaldo has to be absent for a short rest, Al Ahli still has a chance to hold a draw. But if Ronaldo still appears in the match, it would be better to choose to bet on Al Nassr win -1 with higher odds of around @2+.
Al Nassr should win the game with or without Ronaldo presence because they have being defeating Al Ahli Saudi for the past games that they have played. Ronaldo being fit for the match shouldn't make him to start because he needs to rest after playing during the international break and most of the players in the league didn't have the time play he is having and also considering his age. He shouldn't be over used before he gets burnt out and can't perform again. Both clubs don't have a clean record looking at their last played games but since Ronaldo influences is at Al nassr, they should win or the game ends in a draw for both team to share the points.
Al-Nassr cannot afford to lose a single point in every match this season if they want to compete with Al-Hilal in the race for the title this season. with Ronaldo or without Ronaldo. But if we look back at how Al-nassr performed without Ronaldo then we will see a deadlock in the attack line. This team's accuracy sometimes becomes not so good when Ronaldo is not there due to absence or something. I don't know how, but the Al-Nassr players always seem to get better when Ronaldo is present. Talisca and Mane can be expected in the attack line. but they sometimes lose their consistency. So I hope Cristiano Ronaldo can play even if only in the second half. Because considering his age, he should be given a little rest. And it's okay to keep him out of the starting eleven for a while in the next match against Al-ahli.