The 50-year-old fired a second round two-under 70 on Friday to sit four strokes behind the leaders and said if he can get a better feel for the course's large, sloping greens, he has a shot at winning his sixth major title.
"I'm driving like a stallion. I'm hitting the ball great," Mickelson told reporters.
"And I'm putting awful. If I get that fixed for the weekend, I'm going to make a run."
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Mickelson is swinging a 47.5-inch driver at the tournament and has been long and accurate from the tee box but is putting well below the field average, highlighted by an ugly three putt on par-four third for bogey on Friday.
"I'm very frustrated and disappointed with the way I've putted," he said.
"I've let eight, nine, 10 shots on the green, and it's pathetic. I'm going to fix that and hopefully make a run. But you can't make those mistakes in this field.
"But we've got 36 more holes, and I'm playing well enough to keep me in it."
This year's Masters is truly like no other, having been pushed from April to November with no fans are in attendance due to the COVID-19 pandemic.
But Mickelson said his most important supporter is all the gallery he needs - his wife Amy.
"She is the most charismatic, intelligent, dynamic person I've ever met, and her energy and support means more to me than anything," he said.
"To be able to see her out here and have her on holes that she's never been able to see before, like 12 and 13, is an experience of a lifetime for both of us. I'm so happy she's here." (Reporting by Rory Carroll in Los Angeles; Editing by William Mallard)
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