Ah-Ahli fans launched missiles at Cristiano Ronaldo and his Al-Nassr team-mates while chanting 'Messi' during a Saudi Pro League match.
Otavio fell to the floor when one plastic water bottle exploded on his head.
Ronaldo and his pals were celebrating after he had seemingly put them 1-0 in front, though his goal was ruled out for offside.
He would later convert a penalty to win the Friday game 1-0, with Sadio Mane and Roberto Firmino reuniting afterward.
Those good feelings were marred by the Ah-Ahli delinquents, who pelted the opposition players with multiple objects.
Ronaldo is used to the 'Messi, Messi' chants by now, and so is his Argentine counterpart.
Messi was forced to hear the name of his rival during Inter Miami's 3-1 win over Nashville in the last 16 of the CONCACAF Champions Cup on Thursday.
He responded perfectly by scoring within 14 seconds of the chants starting, silencing the crowd.
And Ronaldo had the last laugh when he scored the only goal in Al-Nassr's 1-0 win over Ah-Ahli, seeing his side move nine points clear to cement their place in second position.
After scoring his penalty, he and his teammates got playful, doing tricks with new water bottles when they were launched and inviting more.
Ronaldo is the top scorer in the Saudi Pro League this campaign having scored 23 goals for Al-Nassr in the league.
That said, they are nine points off unbeaten league leader Al-Hilal, so their title chance is diminishing.
They are also out of the Asian Champions League, having lost to Al-Ain on penalties in the quarter-finals.
#AlAhli fans throw water bottles at #AlNassr players, but the players respond with humor and fun.
That match descended into anarchy at full-time, with a scuffle breaking out between players.
Mane even grabbed a player by the throat during the match but escaped punishment.
