Danny Willett is likely to become the first defending U.S. Masters champion to miss the cut since 2004 after struggling to a six-over-par 78 in the second round on Friday.
The Englishman, who carded 73 on Thursday, made a quadruple-bogey eight on the first hole before a solitary birdie and three bogeys, including one at the last, left him seven over par for the tournament.
The projected cut score is six over, although that could change with high winds continuing to make low scoring difficult at Augusta National.
Willett, 29, shot a flawless 67 in the final round at Augusta last year to win his first major title.
Canadian Mike Weir was the last Masters champion to miss the cut 12 months after donning the Green Jacket.