Wales scrum-half Richie Rees admits it is "hard to accept" missing this season's entire RBS 6 Nations Championship.
Rees and the Cardiff Blues have decided not to appeal against a 12-week ban imposed by an independent European Rugby Cup disciplinary panel earlier this month. The 27-year-old pleaded not guilty to making contact with the eye area of Northampton and England hooker Dylan Hartley during a Heineken Cup on December 19.
Rees said: "Having sought legal advice, with the support of the Blues and Welsh Rugby Union, we have decided not to appeal against the decision. Naturally, I am disappointed at the outcome of the hearing and to be suspended for 12 weeks. Missing out on the Six Nations and some crucial games for the Cardiff Blues is hard to accept."
He added: "I felt it was worth looking at the possibility of an appeal as I am desperate to play for the Blues and Wales and naturally feel frustrated and disappointed at the outcome.
"However, I will now be concentrating on training hard in anticipation of the Magners League run-in for the Blues in March and April, and hopefully I can still be part of the Rugby World Cup preparations with Wales."
Rees provided scrum-half bench cover for Mike Phillips during the recent autumn Test series, scoring a try against Australia, and could have expected to be named in Wales coach Warren Gatland's Six Nations squad later this month.
Ahead of the World Cup, Wales face the Barbarians in Cardiff on June 4, before playing England home and away and then Argentina in World Cup warm-up games during August.