The FC Augsburg midfielder rifled home in the 85th minute, much to the relief of Korea's fans and coach.
The FC Augsburg midfielder rifled home in the 85th minute, much to the relief of Korea's fans and coach Uli Steilike whose evening had threatened to end in disaster.
Marat Bikmaev had given the Uzbeks a shock lead but South Korea levelled through Nam Tae-Hee before Koo's clincher put them level on points with Group A leaders Iran, who play Syria later.
Bikmaev pounced on a defensive howler in the 25th minute when goalkeeper Kim Seung-Gyu had to charge out of his box to clear a loose ball, only for his effort to drop straight to the Uzbek.
And Bikmaev took his chance beautifully as his long-range chip sailed over the backpedalling Korean goalkeeper and defenders, and straight into the hosts' goal.
Uzbekistan then frustrated South Korea with some tight defending before Nam finally broke through in the 67th minute after a deep cross from Park Joo-Ho.
And with five minutes left, towering forward Kim Shin-Wook headed down a cross for Koo, who drove it past goalkeeper Aleksandr Lobanov to complete the comeback.