Rafael Nadal admits that he could find things tough on his return to competitive tennis next week after seven months on the sidelines.
The Spaniard arrived in Santiago on Friday amid great expectation and was received by Chilean president Sebastian Pinera at his residence, La Moneda Palace.
Nadal, an 11-time Grand Slam winner, is preparing to take part in the ATP event in Vina del Mar, 120 kilometres to the west, next week.
He will team up with Juan Monaco in the doubles on Tuesday, before his singles return on Wednesday.
Nadal is a wildcard entry into the singles event, and sought to play down talk of a winning comeback after such a long time on the sidelines.
"Undoubtedly the clay surface is a little less aggressive on my knee," he said, explaining why he chose to return in the first clay-court tournament of the calendar year.
"My aim is to compete courageously and hopefully the knee will stand up to it.
"There is always the possibility that I will lose in the first round after so many months without competing."
World number five Nadal won the last of his 11 Grand Slam titles to date at last year's French Open but has not played a competitive match since losing to Czech outsider Lukas Rosol in the second round at Wimbledon last June.
"Of course I still feel pain in the knee that sometimes stops me from playing, but you have to start sometime and I am here to try and give my best and hope that my knee comes through it," he added.
"The injury looks much better. There is no risk that I will suffer any setbacks here."