Diego Maradona claims his guidance on the training ground helped transform a luckless Lionel Messi into one of modern football's deadliest free-kick takers.

The legendary Maradona coached Barcelona superstar Messi during Argentina's eventful 2010 World Cup campaign.

Messi won his second Ballon d'Or that year but failed to get on the scoresheet in South Africa as the Albiceleste crashed out in the quarter-finals, losing 4-0 to Germany.

Despite Argentina's talisman not scoring at that tournament, Maradona feels that period was when the forward was at the peak of his powers.

But the new Gimnasia y Esgrima La Plata boss believes a dose of his own wisdom was needed to elevate the attacker's dead-ball skills to the world-class level they have reached.

"Messi, in the World Cup I was in charge, all the goalkeepers [we played against] were the man of the match," Maradona said.

"He hit all the posts. Now he can't miss. It's a simple story.

"I had the best Messi and nobody can tell me otherwise, because he was able to skip past up to five players. A phenomenon. 

"But he had an issue with free-kicks. When we finished every training session we kept Leo behind so he could practice, and he started to hit the post. I didn't teach him how to take a free-kick. 

"Then he asked me how I was able to score."

Maradona described his advice as being simply to "hit it in the middle".

"And he replied, 'But I hit it in the middle and the ball goes this way or that way', and I told him, 'Don't worry, you're going to make it'," the former Napoli favourite added.

"Now he just can't miss."

Messi, now 32, has forged a reputation as a feared free-kick taker, his most notable effort last season a sublime strike from beyond 25 yards against Liverpool in the Champions League semi-finals.

Maradona left his national team post after the World Cup nine years ago but has returned to his homeland to take charge of top-flight Gimnasia.