San Antonio coach Gregg Popovich said last month that Ginobili should "definitely not" play in the Olympics if his sprained left ankle, which he injured early in the playoffs, doesn't improve.
Ginobili returned to Argentina earlier this month and has remained in daily contact with Popovich, according to the newspaper. The guard told Popovich he has had "zero pain" in the ankle.
"I had been playing more the last few days and it had improved," said Ginobili, who has been playing more in team practices. "It feels great, and that makes me very happy."
Ginobili joins the 12-man roster as Argentina looks to defend the gold medal it won in 2004. The team opens play against Lithuania.
Information from The Associated Press contributed to this report.