Phil Mickelson has turned to fasting to help improve his play ahead The Open Championship this week.

The 49-year-old posted a video on Twitter Sunday revealing he is down 15 pounds ahead the major in part thanks to a six-day fast. 

"I don't know if it's going to help me play better or not,'' Mickelson said in the video. "But I'm willing to do whatever it takes to try and get my best back.''

The five-time major champion has missed the cut in four of his past six starts since winning the AT&T Pebble Beach National Pro-Am in February. He finished tied for 52nd at the U.S. Open at Pebble Beach last month, 17 strokes behind champion Gary Woodland.

Mickelson will take to the course at Royal Portrush Golf Club in Northern Island Thursday in a group with Shane Lowry and Branden Grace. He won the tournament in 2013.