Spain's Rafael Nadal shook off an inauspicious start to roll to a 6-3, 6-2 victory here over Argentine qualifier Federico Delbonis at the VTR Open, his first singles match after a seven-month hiatus due to a knee injury.

Nadal dropped serve in the opening game of Wednesday evening's match but broke Delbonis' serve in the fourth and eighth games to take the first set in just over 50 minutes.

The second set was mostly smooth sailing as Nadal jumped out to a 4-0 lead before the Argentine got on the scoreboard.

The 11-time Grand Slam champion showed some vulnerability when under attack but his heavy ground strokes and superior consistency ultimately gave him a decisive edge in the match.

Nadal, a former world No. 1 whose ranking has fallen to No. 5 due to his extended absence from the ATP Tour, said afterward that he felt comfortable on court and thanked the crowd for its enthusiastic support.

"I felt good, very happy to play a match again in singles competition; the truth is I couldn't have done it in a better place," Nadal, who teamed with his good friend, Argentina's Juan Monaco, to win a doubles match on Tuesday, told reporters.

Asked about his physical condition, Nadal said his knee held up and he felt good even though Delbonis made him "run hard."

In Friday's quarterfinals, Nadal will square off against the winner of the match between Spaniards Albert Montañes and Daniel Gimeno Traver.

The VTR Open is a small clay-court event in Viña del Mar, a resort city located 120 kilometers (75 miles) northwest of Santiago, the Chilean capital.

The Spaniard also is scheduled to play two other small clay-court tournaments in February - the Brazil Open in Sao Paulo, which starts Feb. 11, and the Mexican Open in Acapulco, which begins on Feb. 25.

Nadal had not played in South America since 2005, when he won his second of 50 ATP Tour singles titles in Costa do Sauipe, Brazil.

The Spaniard began last summer on a high note by capturing a record seventh French Open title in early June with a victory over world No. 1 Novak Djokovic of Serbia in the final.

But he suffered a shock second-round exit at Wimbledon a couple of weeks later at the hands of unheralded Czech Lukas Rosol, considered one of the biggest upsets in the history of that prestigious tournament, and did not compete again until this week.

Nadal withdrew from last year's Olympic Games and the U.S. Open due to the injury.

He had planned to return to action in late December in Abu Dhabi, but a stomach virus forced him to withdraw from that exhibition tournament and he also pulled out of the recently concluded Australian Open.

Nadal, known for his physically demanding style of play and outstanding defensive skills, has struggled to stay healthy during his career, having been forced to withdraw from each of the four Grand Slam events due to various injuries. EFE