England and Saracens winger Chris Ashton will miss the entire Six Nations after losing his appeal against a 10-week ban for making contact with the eyes of Ulster's Luke Marshall.
The judicial officer viewed the tackle, which occurred in the first half of a European Champions Cup match on 16 January, as a red card offence.
But Saracens argued that the 10-week penalty was too severe.
Ashton said he was "incredibly disappointed" at the outcome.
"I now plan to look ahead to the rest of the season and work as hard as I can during my ban," he added in a statement on the Saracens website.
"I vehemently maintain that I have never made an attempt to intentionally make contact with the eye area of any other player.
"To miss out on the chance to represent my country and Saracens during this period is extremely disappointing, but the judgement stands and it is one that I will respect and accept."
Former England team-mate Toby Flood also believes Ashton had been treated badly.
In a post on his Twitter feed, Flood called the original decision "horrible" and said Ashton had been the victim of "incompetence" in the subsequent appeal.
England open their Six Nations campaign against Scotland on Saturday.
Anthony Watson and Jack Nowell will start on the wings at Murrayfield as England look to get off to a winning start under coach Eddie Jones.
Ashton will be free to play again on 28 March.