Leicester prop Marcos Ayerza will miss the Heineken Cup quarter-final clash with Leinster on Saturday after being handed a two-week ban by the RFU.
He clashed with Harlequins' prop Joe Marler in a Guinness Premiership game last Saturday in which both props were sent off.
Leicester's Ayerza butted Marler, who was also banned for two weeks, and the Quins player reacted by punching the Argentine twice.
Jeff Blackett, chairman of the RFU disciplinary panel, said: "This was unacceptable behaviour which was captured on live television and not something we want to see in our game.
"That said, both offences were deemed to have a low-end entry point for sanction.
"The starting point for Ayerza striking with the head was four weeks, reduced to two for his guilty plea and relatively good record.
"Marler's sanction did not alter from the two-week entry point because, despite his guilty plea, his previous disciplinary record counted against him."