Cardiff Blues have revealed that scrum-half Lloyd Williams will be out of action for around four weeks following a knee injury suffered against the Ospreys over the weekend.
The Wales international suffered grade two medial ligament damage that will see him sidelined for about a month, with a possible return against Ulster in the last match of the regular PRO12 season.
Williams, son of Wales and Lions No 9, Brynmor, made his senior Blues debut against Leinster in Cardiff in March 2010.
He was called into the international ranks by Warren Gatland the following year and made three appearances as a replacement in Wales' run to the 2011 World Cup semi-finals, scoring tries against Fiji and Namibia in New Zealand.
Williams has made two starts for his country in total, coming off the bench 11 other times.
The 23-year-old appeared twice as a substitute in Wales' 2012 Grand Slam and five times, coming on for Mike Phillips, as they retained their Six Nations Championship title last month.