(Adds quotes, details) VINA DEL MAR, Chile, Feb 6 (Reuters) - Rafa Nadal overcame a slow start to beat Argentine Federico Delbonis 6-3 6-2 and advance to the third round of the Chilean Open with his first singles victory in seven months on Wednesday.
Nadal lost his serve in the first game but quickly hit back, taking command of the match and winning the first set in 50 minutes at the Pacific resort city of Vina del Mar.
The French Open champion seemed surprised when Delbonis took a 2-0 lead, but with some fierce shots he put things in their place.
The former world number one began to vary his game and showed greater mobility in a one-sided second set which he wrapped up in 38 minutes.
"I feel happy to be playing singles again. It's been an important day for me," Nadal told local television after the match.
"Thanks for supporting me. I'd never dreamed of a comeback like this," he added in front of an ecstatic crowd.
"It was a tough start. Federico played really well and forced me to run a lot".
Nadal took advantage of four of his eleven chances to break Delbonis's serve.
The Spanish left-hander had been out with a knee injury since losing to Czech Lukas Rosol in the second round at Wimbledon in June.
"I'm happy the knee responded well," Nadal added.
In the quarter finals, Nadal will play against the winner of Thursday's match between Spaniards Albert Montanes and Daniel Gimeno-Traver.
The 26-year-old Nadal, whose plan to resume at the end of 2012 was delayed due to illness, will continue playing on his favourite clay surface at two other Latin American events this month, the Brazil Open in Sao Paulo next week and the Mexico Open in Acapulco from Feb. 25. (Writing by Javier Leira; editing by Rex Gowar/Ian Ransom)