KALININGRAD, Russia -- Nigeria coach Gernot Rohr admitted his young team had been "naive" in a 2-0 loss to Croatia in their opening Group D game Saturday, continuing a dismal recent record at World Cups.

A Luka Modric penalty 20 minutes from time and a first-half own goal sealed victory for a Croatia side brimming with technical ability, and the Super Eagles -- who brought the youngest squad to Russia -- have now won just one of their last 13 games on football's biggest stage. 

"We are disappointed but we must recognise Croatia were better tonight and my young players made some mistakes," Rohr told reporters after the game in Russia's European exclave of Kaliningrad. 

With rivals Argentina and Iceland only managing a 1-1 draw earlier Saturday in Saransk, both sides had a chance to take control of Group D.

Nigeria, knowing they were always likely to struggle for possession against a central one-two of Modric and Ivan Rakitic, were content to sit back and allow Croatia to come to them.

After 10 minutes, Juventus target man Mario Mandzukic teed up Ivan Perisic at the edge of the area only for the Inter Milan forward to blaze over.
Croatia, semi-finalists at France '98, have struggled to live up to the lofty expectations borne of an embarrassment of midfield riches, and meekly lost their World Cup opener 3-1 to hosts Brazil four years ago.

There is a sense of now-or-never for the Balkans nation at this tournament and Modric said his side would lift their game when they meet Lionel Messi's Argentina in their next match.

"It's going to be a very difficult match. They have huge amounts of quality, but this win will really boost our confidence and we are going to up our game."

The last time Croatia won their opening group game was back in 1998, and coach Zlatko Dalic said he was glad the squad had put that unfortunate record behind them.

"We were disciplined and we deserved the win. We fought for this," he told reporters.

Nigeria's average age heading into Russia was a little over 25 years old and at times the experience gap showed.

Rohr kept faith in 19-year-old keeper Francis Uzoho but the Deportivo stopper's first real action was picking the ball out of the net.

Just after the half-hour mark, Mandzukic, industrious in his hold-up play, chested a Andrej Kramaric cross back to Ante Rebic, whose fizzing shot was blocked. The resulting corner saw Rebic return the favour with a near-post flick on met by a diving Mandzukic.

Oghenekaro Etebo, up until that point one of Nigeria's best performers, was wrong-footed and bundled into his own net.

Nigeria responded well, with Arsenal forward Alex Iwobi's shot from a cleared free kick blocked on 45 minutes and his Premier League colleague Victor Moses shooting wide from 30 yards on the stroke of half time.

They had the best of the start of the second period, forcing Croatia to bat away three corners in succession, before Moses again snatched a shot wide of Danjiel Subasic's left upright.

But just as Nigeria showed some signs of life, in the 71st minute William Ekong held down Mandzukic from a cross in the area and referee Sandro Ricci immediately pointed to the spot.

Modric's gilded right foot guided it to Uzoho's right side.

"We didn't concede a goal from open play, only from set pieces so this is not a question of tactics," Rohr said.

"Sometimes we were a little bit naive on set pieces but we will work on it."

Nigeria play Iceland on June 22 in Volgograd and Rohr insisted his team could still make it out of what is a highly competitive group.

"We are only one point behind (Iceland) and all is in our hands so let's be positive. Let them learn from this defeat and try to do better," said the former Bordeaux coach. 

Despite fears pre-match, there was no reports of any racist chanting from among the near-capacity crowd in Kaliningrad.(AFP)