Argentina coach Maradona also said the debate as to whether he or Pele was the greatest footballer ever will end and when the 22-year-old's career is over it will be clear who was the best.
"He's at a select level, being the best in the world and a star at Barcelona. Lio is playing kick-about with Jesus," Maradona said the day after compatriot Messi's stupendous four-goal performance in Barca's 4-1 win over Arsenal in the Champions League.
"There are moments when you are invaded by loneliness, but you have to be strong so you don't end up doing things one did," he said, apparently referring to his drug addiction during his playing days.
"I spoke to him a lot about this," added Maradona speaking to Radio Metro in Buenos Aires.
Maradona said that after Argentina's World Cup warm-up against Germany in Munich on March 3, a 1-0 win, he spent two hours with Messi talking about many issues.
"I told him I'd done my thing, now he has to make his career and at the end we'll see who was the greatest of all time. But he's on the right path. I saw that he's mature and full of will," Maradona said.
"How could I not be happy for Messi to win the World Cup. The Maradona and Pele polemics will end and the best thing is that Messi is Argentine."
Maradona was speaking publicly for the first time since he was bitten on the upper lip by his pet dog. He said the dog, which was under medication, was not to blame. He had picked her up while asleep and she had woken suddenly and lashed out.
Argentina are in Group B at the World Cup in South Africa starting on June 11. They face Nigeria, South Korea and Greece.
