The double defending champions were leading 2-0 till the 31st minute when the South Koreans, the joint champions with India last year, pierced open the Indian defence with their brisk pace to begin the fightback before pumping in three goals.
India, outright winners of the Azlan Shah Cup in 2009 and joint champions in 2010, failed to match the speed of the young Korean side, who at one stage were reduced to nine players after the referee flashed green cards to two players following their vehement protest, resulting to their temporary suspension.
It was South Korea who forced an early penalty corner in the eighth minute but Hong Eun-Song shot wide.
India took the lead in the 20th minute from their first penalty corner with Diwakar Ram sounding the board with a powerful grounder after Dhananjay Mahadik squared the ball to him.
Three minutes later, the Koreans got another penalty corner and a mid-field ruckus followed after umpire Martin Madden signalled that Hong Eun-Song`s shot had gone wide to the right.
The Koreans protested strongly, arguing that the ball had gone through the goal netting and play was held up as two Korean players -- captain Lee Seoul-Il and Jang Jong-Hyun -- shown green cards and sent to the sidelines. Play resumed five minutes later after the jury affirmed the umpire`s decision.
With South Korea down to nine players, the Indian strikers had plenty of gaps in opposition defence but they failed to capitalise on that.
S V Sunil missed a sitter by failing to trap Shivendra Singh`s pass across the goalmouth in the 25th minute, but Danish Mujtaba increased India`s lead with a stringing reverse drive from top of the circle in the 27th minute.
The Koreans waged a gallant fightback, dominating the midfield and got their first goal in the 31st minute through Cho Suk-Hoon after he broke down the right flank. The Indian defence grimly held on as South Korea forced two penalty corners in the last three minutes before half-time. on mouseover.
The Koreans capitalised on India`s shaky defence to restore parity six minutes into the second session (41st minute) as Yoon Sung-Hoon deflected Nam Hyun-Woo`s push on a penalty corner attempt.
Yoon Sung-Hoon was also instrumental in South Korea`s match-winner in the 56th minute, earning them a penalty stroke as Vikram Pillay hooked his stick inside the scoring zone. The penalty stroke was duly converted by Jang Jong-Hyun.
India thereafter made some desperate effort to get the equaliser, but the strikers failed to get a clear shot at the goal as South Korea bolstered their defence.
The Korean strikers mounted two counterattacks as 10 Indian players went into the rival half. Goalkeeper Adrian D`Souza brought off two saves to deny the Koreans any more goals.
India play Britain in their second round robin league tomorrow.