The 33-year-old returned to his childhood club Santos in January after a stint in Saudi Arabia and had a crucial impact on his team's survival in the Brazilian top flight, scoring five goals in the last four matches.
"I came for this, to try to help the best way I can. These have been tough weeks for me," Neymar, who played in only 20 of their 38 league games, told reporters.
"I thank those who were with me to lift me up. If it weren't for them, I wouldn't have played these matches because of these injuries, this knee problem. I need to rest, and then we will have this knee surgery."
He did not provide details on the surgery or a timeline for his expected recovery.
Neymar has not featured for Brazil in two years due to a succession of injuries.
In October, national team head coach Carlo Ancelotti said the forward must regain full fitness if he is to earn a recall to the squad for the June 11 to July 19 World Cup in Canada, Mexico and the United States.
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