Liam Williams will miss Wales' opening Six Nations game after being given a three-match ban for his red card in Scarlets' Pro14 derby defeat by Cardiff Blues.
British and Irish Lions back Williams was sent off for his dangerous entry into a ruck.
Williams, 29, entered a ruck and his head made direct contact with Cardiff Blues flanker Shane Lewis-Hughes.
Wales face Ireland in their opening game of the Six Nations on 7 February.
The ban is for three "meaningful matches", with Scarlets expected to bring forward a Pro14 match against Cardiff Blues next weekend to cover European competition postponements.
Scarlets then face Leinster in a rearranged Pro14 match on 30 January before the opening Six Nations weekend, which would complete Williams' ban and make him available for the trip to face Scotland on 13 February.
Williams was playing his first game for six weeks after suffering an injury against Italy in December. It was only his second games in his second stint with Scarlets after rejoining the Welsh region from Saracens.
A Pro14 statement read: "The player was shown a red card during the Cardiff Blues v Scarlets game on January 8 at Cardiff City Stadium by referee Craig Evans (WRU) under Law 9.20 (b) - A player must not make contact with an opponent above the line of the shoulders.
"The player accepted he had committed an act of foul play which warranted a red card. The incident was found to merit a mid-range entry point, which indicates a four-week suspension for this offence.
"The judicial officer determined that there were factors, including the player's remorse, which warranted mitigation of one week.
"The player is suspended from participating in the next three meaningful fixtures for which he is fit and available for selection."
Speaking after the match and before the verdict, Scarlets head coach Glenn Delaney said: "It didn't look like much at real speed but once they've slowed it down and decided what they felt it was, that's the result we got.
"Liam's obviously a quality player and he was adding to the occasion. It takes away the opportunity for him to play for us, which is a shame, but we battled on."
After being shown the red card, Williams told referee Craig Evans: "Going to start playing touch, is it?"
Asked about Williams' comment, Delaney responded: "I didn't hear that. He's just apologetic and he's a good, honest man.
"He just feels disappointed that he's not out there with the boys to keep playing. It's a shame he didn't get to see the contest out."