Police have identified the Leeds United supporter who attacked Sheffield Wednesday goalkeeper Chris Kirkland during Friday night's 1-1 draw at Hillsborough.
The man, who has not been named by police, shoved Kirkland in the face following Leeds' equalizer during a match that was broadcast live on Sky Sports television.
He was identified by members of the public on social networking sites.
South Yorkshire Police's senior investigating officer, Detective Inspector Mark Monteiro, said: "With the public's assistance we have clearly identified the offender who ran on to the pitch during last night's game between Sheffield Wednesday FC and Leeds United FC and who is suspected of assaulting the Sheffield Wednesday goalkeeper.
"We are dealing with the complaint made by the player and we are currently taking statements, collating evidence and making inquiries to locate and arrest the offender."
The police are also using camera footage to identify other offenders who ran on the field or caused incidents Friday.
Kirkland spoke Saturday of his shock at being attacked and urged the authorities to take swift action to prevent it from happening again.
"I was gutted with conceding the goal and had my head down as I kicked the ball down the field so we could restart the game," Kirkland said in a statement released by his club. "I was looking at the ground but when I looked up, I caught a glimpse of someone coming towards me on the pitch.
"I thought he was going to give me some abuse but then suddenly he came at me with both hands and I was stunned. I felt the full force and I was just shocked because you never know what could have been in his hands."
Kirkland was treated by Wednesday's medical team and was able to complete the match.
"I was sore and, as I say, really shocked at what had happened," Kirkland said. "My mind then turned to the possibility of winning the game because we had played ever so well and there was still 15 minutes to go. The rest of the game flew by and then the final whistle came, the adrenalin goes and you reflect on something like that and it was scary.
The shocking scenes were broadcast live on Sky Sports and fans were quick to condemn the trouble on Twitter and Facebook. That led to a suspect being named on sites, and a mobile phone number being circulated.
"I thought of my family watching something like that and it was not a nice feeling to think my daughter saw me assaulted like that," Kirkland said. "I just want the authorities to look at what happened and take the appropriate action because sooner or later, we could be talking about something even more serious."
There were five arrests for various offenses including public order before and after the game, while three people were ejected from the ground and 12 were subject to dispersal orders.
Professional Footballers' Association chief executive Gordon Taylor warned soccer must avoid going back to the dark days of its past after Kirkland's attack, as well as accusations of racism from the Serbian stands towards England Under-21 left back Danny Rose.
"It was a very disturbing incident, and coming in the week with the trouble in Serbia and the attention on racism it's a time to be reminded that we need even more vigilance in football," Taylor told Press Association. "Football's with us every day of the year and it's important that we don't go back to the bad old days with supporters behind fences. There needs to be a full inquiry because of course players can be particularly vulnerable, especially goalkeepers. We need to see positive action from Leeds, the FA and the police."
Information from Press Association was used in this report.