Kazan: Diego Costa rejected claims he intentionally stamped on Iran goalkeeper Ali Beiranvand during a tense 1-0 win over Iran but admitted his crucial match-winner for Spain came down to “luck”.

Frustrated throughout by a dogged defensive display from Iran, Costa courted first-half controversy when he walked towards the Persepolis shot-stopper as he prepared to kick out the ball.

The Atletico Madrid front man got so close he stood on Beiranvand’s toes, causing the keeper to wince in pain and drop to the ground.

The gesture went unpunished by Uruguayan referee Andres Cunha and Costa said it was unintentional. His winner took a deflection off an Iran defender.

“I had a bit of luck with the goal, but I’m happy because it was a very tight game. The important thing today was to win,” he said.