Sao Paulo: Injured Brazil striker Neymar has targeted May 17 for a return to training and vowed to work harder than ever to be ready for this year's World Cup in Russia.

The Paris St Germain player, who became the world's most expensive footballer when he joined the club from Barcelona in August, had an operation on his foot after being injured in a French league game against Olympique de Marseille on February 25.

He has been receiving treatment in Brazil and said he expects to be training exactly a month before the five-times champions play their World Cup opener against Switzerland on June 17. "I get my final exam, if I'm not mistaken, on May 17 and then I'll be free to play," he told reporters at a news conference.

"I had an exam last week, it is all perfect, evolving well, so I hope that continues so I can get back as soon as possible...

"I am having treatment every day, and from the moment I start training I am going to work harder than I ever worked because this is a dream that's coming up, it's a World Cup. I've waited four years for this chance, it's close and I hope to get there in great shape."

Neymar played for Brazil at the 2014 World Cup but missed the catastrophic 1-7 semi-final defeat by Germany through injury. Reuters