Lionel Messi and Sergio Aguero are dangerous scorers, but neither was getting many touches in the first half of Argentina's World Cup opener against Bosnia-Herzegovina.

With his team leading 1-0 at halftime because of an own goal, coach Alejandro Sabella ditched his cautious lineup, bringing Gonzalo Higuain off the bench to play up front with Aguero and Messi. Suddenly, the man many consider the world's best player finally looked like a star on the game's biggest stage.

"The first half was very difficult," said Messi, the Barcelona star who has usually played better for his club than he has for his country. "I was alone and Kun (forward Sergio Aguero) was alone just like I was."

After Sead Kolasinovic's own goal in the third minute, Bosnia — playing in its first World Cup — eased into the match and was the equal of the two-time World Cup champions.

"The early lineup took its toll on us," Sabella acknowledged. "It was an even game until we got going in the second half."

To start the half, Sabella put in Higuain for midfielder Maxi Rodriguez, and midfielder Fernando Gago replaced defender Hugo Campagnaro. That gave Messi support, allowing him to step back and find more space to roam and attack on the dribble.

"When Higuain came in the team lifted itself and began to create chances," Sabella said. "But we do have a few things to improve."

Sabella said he wanted to start conservatively out of respect for the skilled and tall Bosnians.

"There are always details you have to fine-tune as the match goes on," he said. "Taking both halves into consideration, I think we were OK. It was the first game, and those are difficult. But we must improve. At the beginning we had few attacking chances and hardly threatened the goal. So we made the changes."

The adjustments paid off almost immediately.

Messi started to make dangerous runs and struck in the 65th minute. Using a quick give-and-go with Higuain to get space, he cut left, avoided a defender's foot without losing balance and sent a low, left-footed shot off the post behind keeper Asmir Begovic.

The goal — only the second for Messi in three World Cups — gave Argentines packing the famed Maracana stadium a chance to celebrate — and relax. The Argentine fans were always loud, but at times shouted down by Brazilians cheering against their archrival — and for Bosnia.

"There were nerves and anxiety, so it was good to start with three points and a victory," Messi said. "It wasn't perfect, but we got the result."

Sabella was asked to rate his team on a 10-point scale.

"I would give it a six and say we have to improve," said. "And some of that is in my hands."

Bosnia coach Safet Susic also was quizzed about his tactics. He left dangerous forward Vedad Ibisevic on the bench until Messi scored. Ibisevic came on four minutes later and scored Bosnia's lone goal in the 85th.

"I don't regret what I did," Susic said. "I told him (Ibisevic) that playing against Argentina I cannot play two attackers. And besides in the midfield we have very offensive-minded players. Playing two strikers (from the start) would have been very risky."

Argentina plays Iran on Saturday in Group F, and Bosnia plays Nigeria.

The match was the first World Cup game at the Maracana since Brazil lost to Uruguay in the final round of the 1950 tournament, which remains a deep wound in Brazilian football history. The July 13 World Cup final will also be held at the Maracana.


Stephen Wade on Twitter: http://twitter.com/StephenWadeAP