South Korean teams make up half the field in the last eight of Asia's premier club competition but two second half goals ensured Shabab have an excellent chance of reducing the K-League contingent after the second leg in Riyadh on Sept. 22.
Midfielder Fahad Hamad found the net for the White Lions from close range after 68 minutes and Uruguayan Juan Manuel Olivera came off the bench to add another with a cool finish in stoppage time.
The victory against the 2006 Asian champions was all the more impressive as the second goal came after Shabab midfielder Abdulmalek Al Khaibri had been sent off for a second yellow card.
Seongnam Ilwa's Montenegrin target man Dzenan Radoncic scored twice as the home side drew first blood in the only all-Korean tie of the round with an emphatic 4-1 victory over the Suwon Bluewings.
Radoncic put Seongnam in front after eight minutes before South Korea left winger Yeom Ki-hun equalized for the Bluewings from a free kick in the 16th.
Former Colombia international Mauricio Molina restored Seongnam's lead just after the half-hour mark with his fifth goal of the competition.
Radoncic added the third with a header midway through the second half before Suwon's Yang Sang-min turned the ball into his own net to round out the scoring eight minutes from time.
Meantime, champions and co-costs Vietnam have been drawn with three-times winners Singapore in the 2010 AFF Cup, Southeast Asia's premier soccer tournament.
Myanmar will be the third team in Group B and will be joined by a qualifier following Wednesday's draw.
The event, held every two years, will be co-hosted by Vietnam and Indonesia in December following a four-team qualifying event in Laos in October.
In Group A, co-hosts Indonesia, who played in three straight finals from 2000 but have yet to win the tournament, will meet three-times champions Thailand, coached by former England captain Bryan Robson, and Malaysia, who are on a high after winning the SEA Games football title last December.
Two spots were left open in the draw for the first and second-placed teams from qualifying at the National Sports Complex in Vientiane involving hosts Laos, Cambodia, Philippines and East Timor from Oct. 22-26.
Vietnam lifted the trophy for the first time in 2008 with victory over Thailand in the two-legged final and coach Henrique Calisto is bullish about his side's chances once again.
"We aim to defend our title. I believe we will win," he told local media.
Vietnam will prepare by playing North Korea and the Under-23 teams from Australia and Kuwait in a round-robin tournament from Sept. 20-24 to mark the 1,000th anniversary of the founding of the nation's capital, Hanoi.
Singapore coach Radojko Avramovic was happy with his Lions' chances too.
"The group we are in is slightly easier than the other group where there will be three title contenders in Thailand, Malaysia and Indonesia," he told reporters.
"Overall, I am happy with the draw. Our target in this tournament is to reach the final."
