Source: NFL to fine Joey Porter

Pittsburgh Steelers assistant coach Joey Porter will be fined for coming onto the field during Saturday night's playoff game and engaging with players from the Cincinnati Bengals, a source told ESPN NFL Insider Adam Schefter.

Porter was on the field during a fourth-quarter altercation that occurred after Steelers star receiver Antonio Brown was hit across the middle by Bengals linebacker Vontaze Burfict, who was whistled for a 15-yard penalty for hitting a defenseless receiver.

While Brown, who was diagnosed with a concussion, was being tended to by Steelers medical staff, Porter came onto the field -- something that assistant coaches typically are not allowed to do during injury timeouts.

According to NFL rules, medical staff, trainers, attendants and the head coach can come out onto the field to check on the welfare of an injured player. With an injury that appears to be more serious, however, players and other staff sometimes come out on the field to check on the player.

Saturday night's officiating crew in Cincinnati gave Porter the benefit of the doubt, as there was real concern for Brown. The officials were working to clear the field and keep the two teams apart when Cincinnati's Adam Jones tried to confront Porter, resulting in a second personal foul on the Bengals.

The penalties on Burfict and Jones combined to give the Steelers an extra 30 yards of field position on their final drive, setting up Chris Boswell's 35-yard field goal with 14 seconds left that gave Pittsburgh an 18-16 win. Jones complained about the penalty in an expletive-laced rant that was posted late Saturday night on his Instagram account but later was deleted.

Information from ESPN's Coley Harvey, ESPN's Jeremy Fowler and The Associated Press was used in this report.