Ronaldo sustained two bad injuries to his right knee while playing for Inter Milan in 1999 and 2000 but recovered to help Brazil win the 2002 World Cup.

He went on to play for Real Madrid before joining AC Milan in January 2007.

"We're all very sad and worried about Ronaldo," said Milan coach Carlo Ancelotti. "I don't want to say his career is over because only time can put the word end to his career.

"His team mates left the stadium quickly to reach the hospital to check on his condition. Being close to him can help him cope at such a delicate moment of his career."

Milan president Silvio Berlusconi said he believed Ronaldo would be able to resume his career.

"He still has an extraordinary physique. I'm confident in some months time he can return to be the player we all know," Berlusconi told Rai television.

Ronaldo is the all-time leading scorer in World Cup finals with 15 goals in three tournaments.

【体坛英语资讯：No problems after Ronaldo operation - surgeon】相关文章：

★ 娱乐英语资讯：Lindsay Lohan says rehab was sobering

★ 体坛英语资讯：Vultures circling over Federer

★ 娱乐英语资讯：Katie Holmes shows off her signature old Hollywood glamour look

★ 体坛英语资讯：US rely on home advantage against Russia

★ 娱乐英语资讯：Dutch broadcasters unwilling to air controversial Koran film

★ 娱乐英语资讯：Hollywood film, TV actors unions part before contract talks

★ 体坛英语资讯：Tyson Gay: The fastest sprinter in Osaka

★ 体坛资讯：Zhu unfazed by ZZ suspension

★ 娱乐英语资讯：Beyonce and Jay-Z file for a marriage license

★ 娱乐英语资讯：Victoria Beckhams sweet surprise for husband David