RIO DE JANEIRO: Brazil forward Neymar is recovering well from the knee surgery he had after suffering an injury last month but there is still no forecast of when he will be able to return to action, national team doctor Rodrigo Lasmar said on Monday.

Neymar ruptured the anterior cruciate ligament (ACL) and meniscus in his left knee on international duty. He underwent surgery earlier this month in a Belo Horizonte hospital.

The 31-year-old is responding "very well" but the recovery will be long and he must focus on the process, Lasmar told a press conference at Brazil's training center in Teresopolis.

"He's shown, from the first moment that he's following what we're proposing. He knows that it's a process that he's going to need all of us, physiotherapist, fitness trainer, so that we can have Neymar (back) as soon as possible," said the doctor.

Lasmar, who carried out the surgery, said it was not yet possible to set a date for the Al-Hilal player's return.

"Injuries are individual. In general, there are associated injuries that can be just as important, such as a meniscus injury. All this makes the procedure more complex, with a slower recovery period. That's why we don't talk about a timescale," he said.

Neymar joined the Saudi Pro League in August for a reported 90 million euros ($96.28 million), but the former Barcelona and Paris St Germain forward only played five games because he was struggling with muscle injuries.

Brazil, who sit third in the South American World Cup qualifying standings with seven points, face fifth-placed Colombia, with six points, on Thursday. They host leaders Argentina, who have 12 points, the following Tuesday.