Former Open champion Darren Clarke has withdrawn from the Northern Trust Open in California because of a chest muscle injury.
Clarke pulled out of the tournament after scoring a seven-over-par 78 in the opening round on Thursday.
It is the same injury which caused the 45-year-old Northern Irishman miss the recent Qatar Masters.
Clarke's next scheduled event is the Honda Classic in Florida, which takes place from 27 February to 2 March.
Dustin Johnson is the leader at the Northern Trust Open after firing an impressive 66 in his opening round.
Ireland's two-time Open champion Padraig Harrington started his challenge with a 75.