Neymar's physical fitness is developing at a faster pace than Brazil expected, with the World Cup less than a month away.

The Paris Saint-Germain forward has been out of action since February after breaking a bone in his foot.

Neymar's World Cup participation was initially in doubt but, despite missing the end of the season as PSG claimed a domestic treble, the former Selecao skipper should be fit for Russia.

At a news conference on Wednesday, Brazil fitness coach Fabio Mahseredjian suggested Neymar is ahead of schedule in his recovery.

"Neymar has been evolving very well," he said. "It is difficult to speak in percentages, we always want to improve more.

"We do not know where an excellent athlete can reach, but I can say that his evolution is above our expectations."

While Brazil are happy with the progress being made by Neymar, there was worse news on Juventus winger Douglas Costa.

"We knew that we would have two exceptional situations: Neymar and Fagner," said team doctor Rodrigo Lasmar.

"But we had a surprise, which was Douglas Costa. He complained of a pain in the back of the thigh in the last game for Juventus.

"Do not expect to see Douglas Costa on the field in the next few days."

Costa is a doubt for Brazil's first warm-up match ahead of the World Cup, with Croatia their opponents on June 3 at Anfield.