Shehab, seeded fourth in the competition, suffered defeat at the hands of Mohammad Asif whose suprise win earned the Pakistan national champion a spot in the quarter-finals.
Al Joaker, the No 7 seed, made a fine start with 4-2 victory over India's Yasin Merchant, a two-time Asian champion and the third seed, earning him a tie for the second spot.
However, the upshot was not enough to carry him through to the next as he lost out on the frame difference to unseeded Egyptian, Mohamed Ibrahim Mohamed.
Asif and Shehab provided the fireworks in the last session of the first-round action before the Pakistani won 4-3 with with scores of 0-130, 68-32, 39-84, 61-37, 76-50, 7-99, 67-29.
Shehab made a brilliant start to his crunch match with a riveting break of 129 in the opening frame. But with a little bit of good fortune, Asif won the deciding seventh frame. The top-ranked UAE cueist also saw his campaign ended by the frame difference average following a tie for the second place with Pakistan's Abdul Sattar.
Among those who advanced to the quarter-finals were the top seeded Hossein Vafaei Ayouri of Iran, second seed Thepchaiya Un-nooh of Thailand, unseeded Mohammad Sajjad of Pakistan and fifth seed Noppon Saengkham of Thailand.
Habib Subah of Bahrain and Yaser Ahmed Mohammed Elsherbiny of Egypt were among some of the top seeds to make an early exit from the competition.