By Angus MacSwan
PORTO ALEGRE, Brazil, June 23 (Reuters) - After underwhelming early performances, traditional Latin American top dogs Argentina and reigning African champions Nigeria have something to prove when they meet in their final World Cup Group F match on Wednesday.
Argentina were among the favourites going in to the tournament but despite a much-vaunted front four, they have yet to come alive, with the exception of some moments of match-winning magic from Lionel Messi.
Nigeria, representing Africa's richest and most populous nation, have also laboured to convince as a team.
Nonetheless, Argentina sit atop Group F with six points thanks to their less-than-emphatic wins over Bosnia and Iran.
The Sky Blues have already qualified for the Round of 16 but will still want finish first to ensure an easier opponent - in principle at least - in the next stage.
Nigeria have four points following a dull draw with Iran and a win over first-timers Bosnia. A draw would be enough to ensure qualification but a loss to Argentina could put them in trouble.
Iran, who surprised many with their tenacious, bold play against Argentina, could still seize second place if they beat Bosnia and rack up a better goal difference.
So a game that could see as much anxiety as adventure is on the cards.
Messi's sublime strike against Iran in stoppage time in Belo Horizonte only highlighted the danger of Argentina relying on the Barcelona man too much. It wasn't supposed to be like that.
He and his fellow strikers Sergio Aguero, Gonzalo Higuain and Angel Di Maria form what should have been one of the most formidable attack forces in the tournament, but so far it has been rather blunt.
The defence has also looked shaky, with central defender Ezekiel Garay repeatedly caught off guard against Iran.
"We have a few causes for concern," head coach Alejandro Sabella admitted after the close-shave against Iran.
With other Latin American teams such as Chile and previously unheralded Costa Rica powering ahead and delighting fans along the way, Argentina will need to step up the pace if they are to quickly regain what they see as their rightful place at the front.
"We know we are not playing as well as we are expected," Messi said. "But as we go along in the tournament, we will be improving and we will reach our full potential."
Argentina will be able to count on fervent support - tens of thousands of fans are expected to flood over the border into the southern Brazilian state of Rio Grande do Sul, a region which shares its gaucho culure but harbours an intense soccer rivalry.
Nigeria may take heart from the fact that they made a slow start in the African Nations Cup before going on to take the title last year.
The Super Eagles cannot afford to give anything away at the back but will need to hunt for goals if they are to be sure of qualifying for the Round of 16 for the first time since 1998.
Playing in their fifth World Cup, Nigeria's performance against Bosnia was an improvement on the Iran game, when they look bereft of ideas. But their defensive frailties were exposed on several occasions and that could prove fatal with a hungry wolf like Messi on the prowl. (Editing by Justin Palmer)