Mickelson, playing in this week's MasterCard Colonial in Fort Worth, Texas, said he couldn't make Jack Nicklaus' event due to his schedule.
'If I played that would be seven in a row and I couldn't get that to work,' Mickelson said.
The Colonial is Mickelson's third consecutive tournament. He is scheduled to compete in next week's Kemper Open, as well as the FedEx St. Jude Classic and the U.S. Open at Southern Hills Country Club in Tulsa, Okla.
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