Brazilian retired soccer player, Ronaldo Luís Nazário de Lima attends a session of the 13th edition of the Dubai International Sports Conference, at Madinat Jumeirah in Dubai on Jan 2, 2019. (MARCO ALPOZZI / LA PRESSE / AFP)

SAO PAULO - Brazilian football great Ronaldo has urged compatriot Neymar to stay fully focused ahead of this year's World Cup, believing the Paris Saint-Germain forward holds the key to the team's fortunes in Qatar.

Neymar has struggled with injuries and inconsistent form since his world record 222 million-euro move to PSG from Barcelona, prompting many to believe he will fall short of his career potential.

However, two-time World Cup winner Ronaldo believes that the 30-year-old, if fully fit and focused, could prove the difference at the showpiece tournament, to be played from Nov 21 to Dec 18.

If Neymar is 100 percent physically and focused, we will have a big chance of taking home the trophy. That's why we're hoping that Neymar can be at his best and bring happiness to Brazilian people.

Ronaldo Luís Nazário de Lima, Brazilian football great 

"Brazil will always be favorites, regardless of the competition they are playing in," Ronaldo said during an event in Sao Paulo on Wednesday.

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"This World Cup will be no different. If Neymar is 100 percent physically and focused, we will have a big chance of taking home the trophy. That's why we're hoping that Neymar can be at his best and bring happiness to Brazilian people."

Ronaldo was the hero of Brazil's triumphant 2002 World Cup campaign in Japan and South Korea with eight goals, including two in the final against Germany. He was also a member of the Brazil squad that won the 1994 World Cup in the United States.

Neymar, who has scored 74 goals in 119 international appearances, has never made it pass the World Cup's quarterfinal phase.

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"Hopefully he can leave off-field matters aside and concentrate on what is happening on the pitch. He is an ace, perhaps one of the greatest in the history of Brazilian football," Ronaldo said.

"We have a great team with great players. But Neymar, in particular, is very different technically and physically. That's why he can make a difference and be decisive in Qatar."

Brazil has been drawn in Group G against Serbia, Switzerland and Cameroon.