Gloucester flanker Andy Hazell has been banned for 14 weeks for striking Mont de Marsan's Sebastien Ormaechea.
The 34-year-old was sent off for the incident which occurred in the 55th minute of his side's on 11 October.
Independent judicial officer, Roger Morris, imposed a top-end ban of 16 weeks and added two weeks because of Hazell's disciplinary record.
However, the ban was reduced by four weeks because Hazell pleaded guilty.
He will be free to play again on Monday, 21 January 2013.
A European Rugby Cup statement said: "The judicial officer determined that Hazell has intentionally struck Ormaechea with both the fist and the knee."
After the game, Gloucester director of rugby Nigel Davies suggested Hazell had been gouged in the eye before he lashed out.
And Hazell said he lashed out after someone had tried to "severely injure" him.