The 2002 FIFA World Cup semi-finalists suffered a 22nd minute setback when Qatar forward Yousef Ahmed Ali put the hosts ahead. However goals from Lee Keun-ho, captain Kwak Tae-hwi, Kim Shin-wook and Kim Chi-woo put the visitors on course for an eighth consecutive world finals, stretching back to Mexico in 1986.
Qatar, who began their campaign in the final Asian qualifying phase in style when they snatched an away 1-0 win against Lebanon last week, are still looking for their first ticket to the finals and a win over the South Koreans could have put them in a happy frame of mind for the remaining matches in the grueling year-long campaign.
However, that was not to be as the Koreans took their time to settle down in the Arabian summer heat before beginning to dominate the Qataris with their superior ball-passing skills and calculated intent.
Qatar dominated play initially, Ali scoring off a sliding shot after outpacing two Koreans on the left flank, but their joy lasted only three minutes as the Koreans struck in the 25th minute when Lee Keun-ho rose high to head the ball in from close off a delicate chip from Kim Bo-kyung.
The Koreans stepped up their game in the second half, giving the Qataris no respite with their well coordinated attacks, and they went ahead through skipper Kwak Tae-hwi who headed in a corner with ease.
With the Koreans holding complete sway, Qatar spent the rest of the match chasing shadows. In the 63rd minute Korea Republic struck their third goal with Kim Shin-Wook easily tapping in off a pass from Lee Dong-gook as the Qatari defence was caught napping again.
The Koreans finished off in style as Kim Chi-woo found the mark with a header off a corner.