Teenager Musab Al Juwayr scored the crucial spot kick as Al Hilal beat CAF Champions League winners Wydad Casablanca 5-3 on penalties (1-1 after extra time) on Saturday to set-up a Club World Cup semi-final with Flamengo.
Al Juwayr, 19, converted after Yahya Attiat-Allah's miss for the Moroccans, playing 350km down the coast from their home city.
Defender Ayoub El Amloud had opened the scoring for the outfit on home soil before team-mate Yahya Jabrane was shown a second yellow card for unsportsmanlike behaviour on the 91st minute.
Midfielder Mohamed Kanno equalised for the Saudis, invited to the tournament, and sent the game into extra time after 94 minutes.
Kanno then followed El Amloud off the field four minutes into the additional half an hour for the same reason.
Al Juwayr secured his side's place in Tuesday's last four tie in Tangier with an effort from the spot on just his 21st senior appearance.
Later on Saturday, the Seattle Sounders from the US play Egyptians Al Ahly with the winners meeting Real Madrid on Wednesday in Rabat.