World No 1 Dustin Johnson will not compete in this week's Valero Texas Open, the PGA Tour announced on Monday.
He reportedly agreed to play prior to Friday's deadline but Ryan Brehm has been confirmed as Johnson's replacement in the field.
No official reason was initially given for Johnson's withdrawal but the player has since released a statement.
"After much careful thought over the weekend, I have decided to withdraw from the Valero Texas Open," Johnson said.
"I now plan to spend the week at home in preparation for next week's Masters. I sincerely apologise to all the sponsors at Valero and all my friends in San Antonio, as I realise this is disappointing news.
"Nonetheless, I have no doubt it will be another great week for the Valero Texas Open."
The Valero Texas Open in San Antonio, which runs from Thursday until Sunday, live on Sky Sports, is considered a warm-up event for the Masters. Johnson won at Augusta last year to be fitted with his first green jacket.
The 36-year-old was also named PGA Player of the Year last season, the second time in which he has claimed the accolade.
Billy Horschel grinds down Scottie Scheffler to win
Billy Horschel claimed his first World Golf Championship title with a 2&1 victory over Scottie Scheffler in the final of the WGC-Dell Technologies Match Play at Austin Country Club.
The 34-year-old kept the pressure on his 24-year-old opponent in an attritional match, which featured only two birdies, to secure his sixth PGA Tour title at the 17th hole after almost four hours out on the course.
Horschel, the 32nd seed, had beaten Frenchman Victor Perez 3&2 in the morning semi-finals, to set up the clash with 30th-seed Scheffler, who had edged out Matt Kuchar 1up in the last four.
Scheffler, the 2020 PGA Tour rookie of the year but still seeking his maiden win, had been in impressive form in his three previous matches over the weekend but he was a little ragged against his more experienced rival.