Manly back-rower Corey Waddell is set to come under scrutiny from the Match Review Committee after he appeared to intentionally headbutt Penrith forward Liam Martin on Thursday night.
Waddell was slammed into the Panthers Stadium turf during a dangerous tackle from Martin in the 30th minute and reacted angrily when he rose to his feet, grabbing his opponent around the collar.
He yanked Martin towards him and the pair bumped heads, inciting other players to run in for a brief push-and-shove.
Watch the incident in the player below.
Lead referee Ben Cummins awarded the penalty to Manly over Martin's tackle but gave a stern warning to the visitors to tone down the aggression.
Sea Eagles captain Joel Thompson pleaded Waddell's case: "He was put in a dangerous position and he reacted."
Cummins countered: "I don't want the reaction there. The penalty's there, let's leave it at that."
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While the 22-year-old was not placed on report, Fox League's Steve Roach believes Waddell could be in some strife for his actions.
"We'll hear a bit more about that, I'd say," Roach said.
Brenton Speed added: "It was just the slingshot effect with the jumper; he pulled the man into him for the headbutt."
The Panthers led went out to a 15-0 lead after 65 minutes until Manly finally clicked into gear to close the gap.
Two converted Sea Eagles tries created a tense finish but Penrith held on for their fourth victory of the season.
Martin was the standout in the victory, scoring a try and running for 104 metres in an aggressive display.