Stephen Keshi blamed a poor first half performance for Nigeria's 3-2 loss to Argentina on Wednesday, but expressed delight at a place in the second round of the World Cup.

The Super Eagles twice levelled the game but were undone by an inspired Lionel Messi, as well as some sloppy defending, though in the end it didn't matter.

Bosnia-Herzegovina's victory over Iran in the other match in the pool ensured Nigeria would finish second and set-up a Last 16 meeting with France in Brasilia on Monday.

"It's an honour and we're very happy to reach the next round," Keshi told reporters. "I think we lost the game because we showed them too much respect in the first half.

"After the break we managed to play our game, attacked more, had more possession and were better overall. But Argentina are a great team and Messi's a great player.

"He's blessed and there's no way you can escape him. Messi's from Jupiter."

It is the third time overall that Nigeria have reached the second round following 1994 and 1998.

Ahmed Musa also scored a brace for Nigeria that shows his rich potential, but it is the poor form of the defence that will be a worry for Keshi ahead of their meeting with a pacey and skillful French team.

Argentina now tackle Switzerland, a decent enough side under a wily coach Ottmar Hitzfeld. Certainly it is no 'gimme', but the South Americans, with magic Messi, will expect to advance.

"We'd already qualified for the next round but it's good to have finished top of the group, that's what we were aiming for," Argentina coach Alejandro Sabella said. "We improved, were more mobile, passed the ball better and were quicker.

"We were better at changing the tempo of the game too, improved our interplay and had a lot of chances. The further into the tournament we go, the more we're finding our rhythm. The structure of the side is getting much better."

Messi himself believes it was Argentina's best performance of the competition so far and has warned opponents that they are an improving unit.

"We were better in this game, regardless of the goals we conceded," Messi said. "We were more threatening today, found the spaces to exploit and had more chances to score. But we still want more.

"The good thing is we improved and it's a wonderful experience with the people here. We're all still chasing a shared dream."