Leinster's Shane Jennings has been banned for three months after being found guilty of eye gouging.
Jennings, 28, was cited for an incident involving London Irish lock Nick Kennedy during last Friday's Heineken Cup fixture in Dublin.
Kennedy reacted furiously at the time and accused Jennings of poking a finger in his eye, although he later claimed to have over-reacted.
At a European Rugby Cup disciplinary hearing in Dublin on Wednesday, Jennings was found guilty "of an act contrary to good sportsmanship in that he made contact with the eye or eye area of Nick Kennedy".
The judicial officer Roger Morris from Wales decided the offence was at the low end of the scale and, having taken into account any mitigating and aggravating factors, he banned Jennings until January 6 2010.
Leinster later confirmed they will launch an appeal.
A statement from the European champions read: "Leinster Rugby is surprised and extremely disappointed with today's ruling even though there was clear evidence from the opposition player that the act was not intentional.
"The ERC disciplinary committee appears to have found that Shane Jennings was careless with his actions, which is a shock to us.
"Shane has an impeccable record and a strong leadership role within the squad as our vice-captain and we will be appealing this decision."
Jennings will miss eight matches for Leinster, starting with Saturday's Heineken Cup trip to Brive and including the back-to-back European encounters with the Scarlets.
He will be available again to Leinster for their Magners League game against Glasgow at the RDS on the second weekend of January.
The Jennings case is the first high-profile incident since the International Rugby Board vowed to clamp down on the "heinous" offence.
The IRB called for global consistency in how offenders were punished following a spate of notorious incidents, including Schalk Burger's clash with Lions winger Luke Fitzgerald in the second Test.
The Lions felt Burger got off lightly with an eight-week suspension when Munster flanker Alan Quinlan was banned for 12 weeks for a clash with Leinster's Leo Cullen in last season's Heineken Cup semi-final.
Meanwhile, Bath flanker Andy Beattie has been suspended for three weeks after being sent off for stamping against Ulster last Friday night.
Beattie, who pleaded guilty at Wednesday's hearing, will miss Sunday's Heineken Cup clash with Stade Francais and Bath's home Guinness Premiership games against Newcastle and Saracens.
Both parties have the right to appeal.