Spanish tennis star Rafael Nadal, who has been out of action for six months due to a knee injury, said he is "delighted" to make his return to the ATP Tour at a Feb. 4-10 clay-court event in the Chilean resort city of Viña del Mar.

Tournament organizers issued a press release Thursday making official the Spaniard's participation in the VTR Open, which offers $400,000 in total prize money.

"I'm delighted to confirm my participation in the tournament in Viña del Mar, in Chile, and I want to thank the organizers for their invitation," the former No. 1 and 11-time Grand Slam champion was quoted as saying in the release.

"Thank you very much and we'll see each other in Viña," Nadal, whose ranking has dropped to No. 4, said.

Nadal's good friend, Argentina's Juan Monaco, won the tournament last year and will be back to defend his title, while Spaniards Pablo Andujar, Albert Ramos and Tommy Robredo also will be in the draw.

The Spaniard had earlier announced that he would play two other small clay-court events in February - the Brazil Open in Sao Paulo, which starts Feb. 11, and the Mexican Open in Acapulco, which begins on Feb. 25.

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

He told Efe in August that he was suffering from a knee ailment known as Hoffa's syndrome, which is also known as fat pad impingement and involves pain and swelling around the bottom and under the kneecap.

The Spaniard began last summer on a high note by capturing a record seventh French Open title 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 has not competed since.

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 Australian Open, which got underway on Monday.

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