The FA has ordered an investigation into how fans were able to get onto the pitch three times during Birmingham's derby clash with Aston Villa last night.
The first top-flight meeting of the teams in 16 years was marred by dozens of Birmingham fans running on to the pitch after each of City's goals in their 3-0 win.
Villa defender Steve Staunton grappled with one of them while another taunted Villa goalkeeper Peter Enckelman after he conceded a bizarre own goal from Olof Mellberg's throw-in.
In a statement, the FA said it was in touch with Birmingham over the incidents. "We are also awaiting reports from the match officials and an FA crowd safety observer," it said.
Birmingham chairman David Gold played down the scenes, attributing them to high spirits associated with the highly-anticipated derby game.
"We have to be careful we don't overreact," he said. "I am really sorry that we are focusing on that one stupid young man who came onto the pitch [to confront Enckelman] and disgraced himself and disgraced Birmingham and spoilt it for 30,000 perfectly-behaved fans.
"We will track him down and he will be banned for life".