A Millwall fan has been arrested after confronting Leeds goalkeeper Casper Ankergren during Saturday's League One play-off clash at the New Den.
Ankergren was apparently attacked as a small number of home supporters poured onto the pitch after Neil Harris scored the only goal of the semi-final first leg in the 71st minute.
Police horses were used to restore calm at the ground, with a Scotland Yard spokesman confirming: "One man was arrested on suspicion of assault."
Speaking after the game, Leeds manager Simon Grayson played down the incident.
"You know that in play-off semi-finals the atmosphere is quite hostile and people get exuberant," he said.
"I thought the authorities handled it well and our players didn't respond to anything.
"I'm just here to protect my players, they're all okay and nothing much was made of it.
"Casper hasn't mentioned it. I wouldn't want to take Casper on if I was a Millwall fan anyway."