ROME (AFP) - Revisiting his injury-blighted past, Brazilian veteran Ronaldo flew to Paris for surgery on Thursday after rupturing a tendon in his right knee during AC Milan's 1-1 draw with Livorno, media reports said as Brazilian media lamented his latest woes.

Ronaldo will almost certainly miss the remainder of the season with Gazetta dello Sport reporting overnight that the 31-year-old faces nine months on the sidelines.

Renowned French surgeon Professor Gerard Saillant will supervise the surgery, according to the Ansa news agency.

The veteran, all-time top World Cup scorer with 15, has played just six matches this term after thigh and calf problems and now has another even worse setback to contend with.

"It is a bad injury but it can be treated as surgical techniques today have improved," Piero Volpi, doctor with Inter Milan when Ronaldo suffered a spate of injuries almost a decade ago, told SkyTV 24.

"I am not pessimistic on Ronaldo's career - but the problem is now he is eight years older than in 2000 and for a sportsman it's always that much more difficult to get back to your top level," Volpi warned.

Italian media speculated whether, after the catalogue of knee injuries that "Il Fenomeno" has suffered in the past, Ronaldo's latest setback might spell the end of the world champion's career.

In November 1999 and again five months later, he suffered similar problems but returned after the best part of two years on the sidelines following surgery by Professor Saillant to lift the World Cup with Brazil, scoring in the final win over Germany and finishing tournament top scorer.

AC Milan owner and former prime minister Silvio Berlusconi said he believed Ronaldo would be back.

"I spoke with Ronaldo yesterday (Wednesday) and said he must believe in himself. He has extraordinary physical potential and I think he can be back within months to being the champion that he is," Berlusconi said.

With Ronaldo having suffered the bulk of his previous serious injuries playing for Inter before joining Real, his latest setback has found sympathy on the black and blue half of town and Inter chairman Massimo Moratti on Thursday wished him well.

"I hope he gets better soon. But clearly one can at the moment speak of a career in danger, as one said previously first time round (in 1999 and 2000)," Moratti said.

"But Ronaldo is tough mentally and physically and the surgeons know him, while he knows what to expect, which should help things," Moratti hoped.

Back in Brazil, local media were aghast at Ronaldo's latest misfortune.,

"A Phenonemon in danger," headlined the Correio Braziliense daily, referring to Ronaldo's "fragile knees."

O Globo daily noted that "now, aged 31, there's not much hope for him" while O Estado newspaper from Sao Paulo added that his contract at Milan "ends on June 30 and it's difficult to see it being renewed."

The Folha de Sao Paulo newspaper said mournfully: "Knee makes Ronaldo cry once more" as it lamented "a script very similar to that of the saddest moment of his career," referring to his previous injuries.

Ronaldo was injured just minutes after entering the fray as a second-half substitute and was taken to hospital.

Milan coach Carlo Ancelotti refused overnight to call time on Ronaldo's career.

"We're all very sorry and worried about what happened to Ronaldo, I don't want to say it's the end of his career because only time can decide whether it is or not," he said.