Six days before the start of the 86th Masters, defending champion Hideki Matsuyama was forced to withdraw from the second round of the Valero Texas Open because of a neck injury on Friday.

Matsuyama, who last season became the first man from Japan to win a major championship and the first Asian to win the Masters, pulled out of the tournament at TPC San Antonio after playing nine holes in the second round. He was 1-over through his first 27 holes.

Matsuyama, who is ranked 12th in the Official World Golf Ranking, hasn't completed a tournament since tying for 20th at the Arnold Palmer Invitational in early March. The next week, he withdrew from The Players because of a back injury.

During a teleconference with reporters on March 22, Matsuyama said he hadn't been able to practice as much as he wanted because of the ailments.

"I've been receiving a lot of treatment, getting prepared," Matsuyama said, through his interpreter. "I'll do my best to prepare well so I can defend my title at Augusta. ... I haven't been able to practice as much as I'd like, but what I have been doing, I feel like I'm on the right track. Hopefully, I can find that same form that I started the year out with."

Matsuyama already has two victories this season, at the Zozo Championship in October and the Sony Open in Hawaii in January.

Matsuyama will host the Champions Dinner at Augusta National next week.

"How [winning a green jacket has] changed my life is a good question," he said. "I haven't really figured that out yet. I know I'm a happier person. I've also noticed people have received me differently ... The one impression that I've had this past year is how people have embraced me and received me and cheered me on."