London - England star Billy Vunipola is set to miss the Six Nations after breaking an arm for the fourth time in two years, Premiership club Saracens announced on Monday.
His injury heaped more misery on the English champions, who on Saturday had been told they would be relegated at the end of the season for salary cap breaches.
The 27-year-old Number 8 suffered the injury early in Saracens' 27-24 victory over French side Racing 92 on Sunday, which kept their hopes alive of defending their European Champions Cup title.
"Billy Vunipola has suffered a broken arm," read a club statement.
"The Saracens No 8 picked up the injury seven minutes into the victory over Racing 92 in the Champions Cup.
"He will see a consultant over the coming days to determine the full extent of the injury before undergoing rehabilitation."
The 51-time capped Australia-born forward, who was instrumental in England's run to the Rugby World Cup final last year, has broken his right arm twice and his left once.
England kick off their Six Nations campaign against France on February 2 in Paris and end with a trip to Rome to play Italy on March 14.