Brazil great Ronaldo believes compatriot Neymar will be back from injury in time to lead a "very strong team" at the 2018 World Cup.

The South American nation were last crowned world champions in 2002, when Ronaldo scored both goals in a 2-0 final win over Germany.

Selecao hopes are high ahead of this year's tournament in Russia, with Brazil losing just once during qualifying to finish top of the CONMEBOL section.

However, much will depend on the health of Neymar, with the Paris Saint-Germain forward battling to be fit after undergoing surgery on a broken metatarsal at the end of February.

"At a World Cup, everyone knows it's a very difficult tournament," Ronaldo told Omnisport. 

"I think Brazil has improved in the last one-and-a-half years with the change in manager. We have a very strong team for the World Cup.

"Neymar getting injured is a big problem for us but I think he will recover soon and he'll be fit for the World Cup.

"But, as I say, it's a difficult tournament. We have very good teams."

Ronaldo - a three-time winner of FIFA's World Player of the Year award - believes Argentina remain one of the leading contenders for glory despite their problems in qualifying.

Lionel Messi scored a hat-trick as Argentina defeated Ecuador 3-1 in a dramatic final round of fixtures, finally securing the two-time winners a place in the field. 

"I think Germany are always strong, Spain is strong as well, England, France, Argentina, with [Lionel] Messi, it's always difficult to win the World Cup," Ronaldo added.

"But we will see a beautiful World Cup. I hope Brazil can win again."