"We're disappointed with how the game finished. We were in control of the game probably up until the 60-minute mark.
"We had enough chances to go two up and kill the game off. We were a goalpost away from doing that."
Nevertheless, the vital away goal could prove the difference when Postecoglou's men host the second leg in Sydney on Tuesday.
With that match in mind, he left Tom Rogic, Massimo Luongo and Jackson Irvine on the bench and gambled with the greenest members of his squad.
It paid off handsomely.
Uncapped Matt Jurman, thrust into a three-man defence alongside Trent Sainsbury and Milos Degenek, looked like an old hand.
Trimmed-down right-back Josh Risdon, capped just three times, was a hive of industry at right wing-back and relieved a high-playing Mat Leckie of his defensive responsibilities and Aziz Behich was lively down the left.
That rejig bore fruit five minutes before the break, when Leckie blazed to the right byline and cut inside to turn a defender and let rip, Kruse timing his run perfectly to divert the shot home.
Under the weight of last month's failure to qualify directly for a fourth straight World Cup, a bobbly pitch and a sea of red to break down, the Socceroos had their work cut out.
Chances came and went as Tomi Juric twice hit the post in consecutive shots and Leckie somehow skied a sitter with ample time.
Captain Mark Milligan, who endured extra attention all night, pulled the midfield strings alongside Aaron Mooy and unwound from 25m to force a full- stretch save from Syrian goalkeeper Ibrahim Alma.
But Syria brought the pace, and none were more searing than Al Somah.
As Australia searched for a killer second goal, the danger man and his cohort amped up the pressure, slicing through the Socceroos' defence with increasing regularity and forcing a succession of corners and free-kicks.
Mat Ryan, hardly called upon in the first stanza, was suddenly in the firing line and made a string of saves including one superb injury-time effort to deny Syria the win.
But there was nothing the Brighton and Hove Albion gloveman could do when Syria were awarded a penalty after contact from Leckie on Al Somah, who duly converted from the spot.
