Quick-fire double gives Al Hilal advantage in Asian Champions League
Aleksandar Mitrovic's 40th-minute penalty put Jorge Jesus's side in front at the Kingdom Arena in Riyadh with Salem Al Dawsari doubling the advantage two minutes later as the Al Hilal winger struck to finish off a devastating team move.
Al Ittihad finished with 10 men after N'golo Kante was dismissed for a dangerous tackle on his former Chelsea team-mate Kalidou Koulibaly with 25 minutes remaining, referee Shuan Evans dismissing the Frenchman after a video review.
The teams will meet again in Jeddah next Tuesday, with the winner taking on either Al Ain of the United Arab Emirates or Cristiano Ronaldo's Al Nassr in the semi-finals next month. Al Ain hold a 1-0 advantage having defeated the Saudi Pro League side in Monday's first leg.
Mitrovic scored from the spot to claim his 30th goal in 31 games in all competitions since joining Al Hilal from Fulham after he had been wrestled to the ground by Madallah Al Olayan.
Al Dawsari then added his side's second when Malcom was released down the right by Ruben Neves's incisive pass from deep and the Brazilian centred for the current Asian Player of the Year to pounce.
Earlier in the day, Ulsan Hyundai claimed a 1-1 draw at Jeonbuk Motors as Lee Myung-jae's late strike cancelled out Song Min-kyu's fourth-minute opener in the first leg of their quarter-final at Jeonju World Cup Stadium.
Lee scored 13 minutes from time to level the scores ahead of the second leg in Ulsan next Tuesday with Jeonbuk's Brazilian striker Tiago Orobo having missed a first-half penalty.
Jeonbuk went in front when Song swept a close-range finish past Jo Hyeon-woo after Lee Dong-jun was released down the right to deliver an inch-perfect cross that unlocked the defence.
The home side squandered the chance to double their lead when Ulsan's Lee Myung-jae upended Lee Dong-jun inside the penalty area but Tiago clipped the bar with his spot-kick.
Ulsan and Jeonbuk will play again next week, with the winners due to face either the Harry Kewell-coached Yokohama F Marinos of Japan or Chinese Super League side Shandong Taishan, who meet in the first leg of their quarter-final in China on Wednesday.