FIFA has said it is looking into the incident after Spanish referee Carlos Velasco Carballo did not even book Zuniga for the challenge. Zuniga has expressed regret for the injury but insisted there was no intention to cause harm."I deeply regret the sad injury suffered by Neymar during the game between Brazil and Colombia," the defender said in a letter sent to Neymar that was quoted by the Colombian Football Federation. "This situation resulted from normal game action and there was no ill-intent, malice or negligence on my part," Zuniga added. Neymar was collecting the ball in the 88th minute when Zuniga launched a jumping challenge from behind and kneed the Brazilian in the lower part of his back.