Leigh Halfpenny has given Wales a late fitness scare ahead of their Six Nations clash with England after missing Friday's captain's run.
A Wales spokesman confirmed the 29-year-old missed the session with illness.
Halfpenny's potential absence from Saturday's match gives Warren Gatland a selection headache, particularly after the full-back's exploits against Scotland last weekend.
The Scarlets man scored 24 points in Wales' 34-7 thrashing of the Scots to help his country to a strong start to their Six Nations campaign.
Should Halfpenny be ruled out of the Twickenham contest, Gatland could choose to promote Gareth Anscombe from the bench, or move fly-half Rhys Patchell to 15.
Halfpenny, who is approaching 700 career points for Wales, has 75 caps for his country.
Wales are looking to become the first team to beat England at Twickenham in the Six Nations since 2012.