Ex-Sunderland striker accused of Anthony Joshua-style punch after Portsmouth's draw with Bristol Rovers
Vaughan, who spent six months at Sunderland last season, joined Pompey in January and made his second appearance for Kenny Jackett's side on Tuesday night.
Portsmouth were held to a 1-1 draw by the Gas at Fratton Park, a result which saw them slip behind Sunderland in League One.
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Hide AdBut it was Vaughan who dominated the headlines after the game, with Coughlan accusing the striker, 30, of assaulting defender Tom Lockyer 17 minutes from time.
"It's a shocker. He has swung," said the Rovers boss. "He's punched him. Anthony Joshua would have been proud of it.
"I'm disappointed the referee didn't see it but hopefully the authorities will look at it because it was naughty.
"I'm all for physical contact but that was below the belt.
"Hopefully the FA won’t ignore it just because we are little old Bristol Rovers."
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Hide AdLockyer protested furiously following the event but wasn't able to continue after receiving treatment.
Referee Neil Hair took no action meaning the indecent could be reviewed.
Portsmouth have now gone seven league games without a win and dropped to fourth following Sunderland's win over Gillingham.
The Black Cats are one point above Pompey in League One and have a game in hand on Kenny Jackett's side.