England powerhouse prop Mako Vunipola is to miss Sunday's Six Nations match with Ireland as he has returned to Tonga for family reasons the Rugby Football Union announced on Tuesday.
The 29-year-old Saracens star -- whose parents are Tongan -- played in the 13-6 win over Scotland having been omitted from the opening defeat by France.
Bath's Beno Obano has been drafted into Eddie Jones' 33-man training squad as cover.
Veteran Joe Marler is set to return at loosehead prop, with Ellis Genge -- who scored the lone try in the Scotland game -- resuming his role as a replacement.
"Mako Vunipola is not included as he has travelled back to Tonga for family reasons," read a brief statement from the RFU after the initial 33-man squad for the game was revealed.
Centres Manu Tuilagi and Henry Slade are both included in the training squad after recovering from injury.
Tuilagi is on track for a return to the side after a minor groin niggle, but Slade's involvement is in doubt given his two-month absence with a fractured ankle.
Sunday's match is a high stakes one.
England will hope to keep their Triple Crown dreams alive and at the same time prevent Ireland maintaining their push for a second Grand Slam in three years.
The Irish beat Scotland and Wales both at home but travel to Twickenham having lost to England on their last two meetings, a rare home reverse in last year's Six Nations and then a 57-15 whipping before the World Cup.