Chandigarh: Ramkumar Ramanathan enjoyed a memorable Davis Cup debut as he notched up a hard-fought victory over Seong Chan Hong of South Korea in the opening singles to hand India a 1-0 lead in the Asia/Oceania Group-I tie here on Friday. Ramkumar will, however, thank the hot and humid conditions here for playimg a part in his win. The 21-year-old Indian was leading 6-3, 2-6, 6-3, 6-5 (15-15) when the Korean suffered a cramp in his right thigh and was unable to continue. The tough conditions took a toll on both players, but Ramkumar seemed to cope better than the Korean. Ramkumar relied on his strong serve and backhand to take the first set. But he paid for committing a seemingly endless string of unforced errors which allowed Hong to claw his way back to level terms in the second set. Ramkumar faced another break chance in the third game of the third set but banked on his strong serve to pull himself out of trouble. The Indian continued to use his serve effectively to clinch the third set and regain the lead. The fourth set witnessed a close battle before Ramkumar broke Hong at 5-5 to take a decisive advantage. With the Indian serving for the set at 6-5, Hong suddenly collapsed while holding his right thigh. The Korean was unable to continue and had to be lifted out of court, thus handing the match to Ramkumar.