Diego Costa: There are so many cameras that you can't play the fool FIFA World Cup 2018 - Iran 0-1 Spain Spain achieved victory through Costa's fortunate goal

Fernando Hierro is on the cusp of guiding Spain into the last-16 after La Roja's 1-0 victory over Iran, and Diego Costa has made clear that, with the presence of VAR, you can't get away with misbehaving.

The Atletico Madrid forward scored the only goal of Wednesday's match, although he knew very little about it as Ramin Rezaeian fired the ball into his knee and past a wrong-footed goalkeeper.

And a potential flashpoint occurred in the first half when Iran's goalkeeper, Alireza Beiranvand, accused the Spanish forward of stamping on his foot.

"I was very calm, there are so many cameras that you can't play the fool," he explained.

"I was sure that I hadn't done anything wrong."

Costa was handed the man of the match award following the win although he accepted that there was an element of good fortune in his goal.

"I had a bit of luck with the goal, but I'm happy because it was a difficult match," he confirmed.

"They've been very defensive, we knew that we would need to be patient. They wasted a lot of time."

Victory in Kazan put Spain on top of Group B, with the former Chelsea goalscorer aware of just how important it was to secure all three points after drawing with Portugal.

"We played a fantastic match against Portugal," he intimated.

"Today we had to play against a very solid opponent. In a match like this the important thing is to win."