ST PETERSBURG • A relieved Lionel Messi said he was surprised by his side's struggles against Nigeria on Tuesday, but that he and his Argentina team-mates were always confident about winning the crucial World Cup clash that secured them a place in the last 16.

The Barcelona forward opened the scoring with a superb goal in the dramatic 2-1 win that sent the South Americans through to the knockout stages behind Croatia in Group D.

"We already knew we were going to win, we were confident that God would help us, that all would turn out well. But we did not expect the complication of the draw, of suffering so much," he said.

After the Africans equalised through a Victor Moses penalty in the 51st minute, Messi said his side got "nervous".

"We had the impression that time was going by faster. That's the reason we started attacking and pressing more and that's how we managed to score," he said.

Deliverance came in the 86th minute, thanks to a strike from defender Marcos Rojo.

Argentina will now need to be more consistent when facing France in the last 16 and, according to Messi, the squad had watched all of France's games and are bracing themselves for the skilful Europeans.

Argentina coach Jorge Sampaoli also defended Messi from perennial criticism that he plays with more effort for Barcelona than for his country.

"Every time Messi plays, he shows that he is a fantastic player, that he is above anybody else. But he needs the support from his team-mates. Only then will he play at his best," said the 58-year-old.

Argentina legend Diego Maradona, who was in the stands, said yesterday he was fine after appearing to be taken ill during the nerve-racking affair. Argentinian media had reported that he suffered a spike in his blood pressure.

"I want to tell everyone that I am fine, that I am not, neither was I, interned," he said in an Instagram post, responding to a media report that he had been taken to hospital.

"In the half-time of the game against Nigeria, my neck hurt a lot and I suffered a decompensation. I was checked by a doctor and he recommended me to go home before the second half, but I wanted to stay because we were risking it all.

"How could I leave? I send a kiss to everyone, thanks for the support!"

A video posted on Twitter after Tuesday's game showed Maradona, 57, needing help to walk.

During the game, Maradona drew attention with his antics in the stands - holding up a huge banner of himself, celebrating wildly after Messi's goal, enjoying the adulation of fans, seemingly falling asleep at one point, and making an obscene gesture with both hands after Rojo's winner.

REUTERS, AGENCE FRANCE-PRESSE