KAZAN, Russia, June 20 (Xinhua) -- Diego Costa's lone goal in the second half gave Spain a 1-0 win over Iran in their World Cup Group B match here on Wednesday.

After a goalless first-half, Diego Costa broke the deadlock for Spain in the 54th minute after his shot bounced past Ali Beiranvand into the bottom-left corner after meeting a pass from Andres Iniesta.

Saeid Ezatolahi almost leveled the score for Iran in the 62nd minute, but the Iranians' cheers were cut short when the goal was ruled offside with the help of video assistant referee (VAR) system.

Wednesday's match opened with Spain launching fierce attacks but failing to find clear-cut chances as the Iranian side put up a strong defense.

The Spanish side made their first threat in the 3rd minute, as Carvajal kicked a speculative shot but was headed away by Iran goalkeeper Ali Beiranvand. Only one minute later, another shot from Spain was tipped away by Beiranvand.

Facing Spain's fierce attacks, the Iranian side tightened their defense to their own half court in the rest of the first half and practically left Spain no chance.

Paces picked up in the second half with Spain desperate to make a breakthrough.

After Costa scored in the 54th minute, the Iranians changed strategy and showed more attacking intents but failed to get even.

FIFA statistics showed that Spain made 17 attempts at the goal throughout the match, while Iran made only five. Ball possession was 69 percent for Spain and 31 percent for Iran.

Diego Costa, having scored three times in the first two matches of World Cup this year, was chosen as man of the match.

"The truth is I had a bit of luck (with the goal)," said the Atletico Madrid star after the game. "But I am happy because it was a tight game," he added.

"We deserve a better result," said Iran coach Carlos Queiroz at the post-match press conference, noting that his team played with a fighting spirit.

But he added that the match itself was a "win" for his team anyway, as his team learned a lot from fighting Spain.

Spain's new coach Fernando Hierro said after the match that he was happy for getting three points, noting that Iran are a strong team.

"It was a difficult game. It is very hard to score against them. They are very direct, tough, very strong physically," he said.

After the second round of Group B matches, Spain and Portugal are jointly leading with four points, while Iran had three points with one win and one loss. Morocco, meanwhile, have practically lost the chance to reach the knockout phase after being beaten twice.

Iran will meet Portugal in their last group match while 2010 champions Spain take on Morocco.

"Everything is open. We are still alive, dreaming. That's it," said Queiroz, not losing the hope for Iran to progress to the next phase through a win over Portugal.

He added that Portugal are a great team with fantastic players but Iran will not be afraid of attacking.

Hierro said he expects a difficult game for every team. "There are 32 brilliant teams here. We are the best national teams in the world. If anyone thinks it is going to be easy, and to win by a landslide, they are wrong. That's the beauty of the World Cup," he said.