Rory McIlroy's green jacket defense appears to be a bit up in the air.
The reigning Masters winner was forced to withdraw from the Arnold Palmer Invitational on Saturday after suffering back spasms during his range session.
"While warming up in the gym this morning, I felt a small twinge in my back. As I started hitting balls on the range before the round, it worsened and developed into muscle spasms in my lower back," McIlroy said.
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"Unfortunately, I'm not able to continue and have to withdraw. I was excited to compete this weekend. I wish the Arnold Palmer Invitational a great finish and look forward to being back next year."
McIlroy finally took home the green jacket in his 17th try last year - it was his first major since 2014, and it made him the sixth golfer to complete the career slam. It was a weekend full of ups and downs, as he set the Masters record for the most "3s" carded, but he had plenty of dropped shots throughout.
Ultimately, he prevailed in a playoff against Justin Rose, who also fell to Sergio Garcia in a playoff eight years prior.
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The last time someone did not play in the Masters the year after winning it was 1954, when Ben Hogan sat out.
McIlroy finished tied for second in last month's Genesis Invitational, won by Jacob Bridgeman, and tied for 14th at the AT&T Pebble Beach Pro-Am, a tournament he won last year.
The Masters was McIlroy's third and final victory of the season last year. He also won The Players and was part of the winning Ryder Cup team at Bethpage Black. It was the first time a road team won the Cup since the Europeans did so in 2014, and it was the first back-to-back Ryder Cup wins since Europe won three straight in 2010, 2012, and 2014.
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