Glasgow Warriors second-row Leone Nakarawa has been banned for three weeks for headbutting Ospreys prop Marc Thomas.
The 26-year-old was cited for the incident after Warriors' 19-16 victory over the Welsh side on Saturday.
Referee George Clancy referred the incident to the TMO at the time but no sanction beyond a penalty was issued.
However, a disciplinary committee on Wednesday found the Fijian, who has the right of appeal, guilty.
Nakarawa was accused of striking Thomas after a second-half collapsed scrum and the all-Irish committee, chaired by Pat Barriscale, deemed his challenge worthy of a red card.
It was regarded at the low-end of world rugby's scale of sanctions yielding a suspension of four weeks.
The ultimate ban was reduced to three in light of mitigating factors including the player's clean record.
A Pro12 statement read: "The player is suspended from playing for three weeks until midnight on Sunday 29 March 2015, taking into account two "down" weeks."
As it stands, Nakarawa will miss Warriors' trip to Munster on Saturday, next Friday's home match against Zebre, and the 27 March match away to Leinster.
His suspension leaves head coach Gregor Townsend facing a testing trio of Pro12 fixtures with limited second-row options.
Jonny Gray and Tim Swinson - as well as Rob Harley, a flanker who can fill in at lock if required - were included in Scotland's Six Nations squad and Tom Ryder was released to Northampton Saints last month.
Club captain Al Kellock and Edinburgh loanee Alex Toolis are the front-runners to fill in should Nakarawa be rendered unavailable, with back-row James Eddie also capable of stepping in.
Toolis was sent west on a short-term deal last week along with team-mate Fraser McKenzie, who has since returned to the capital.
Nakarawa, known for his flamboyant style of play and offloading game, joined Glasgow on a two-year deal in 2013 and signed a further two-year contract extension in December.