MEMPHIS, Tenn. – Phil Mickelson tried a different putting style Thursday at the WGC FedEx St. Jude Invitational – the only question is whether it was a one-day experiment.

After a 1-under 69 at TPC Southwind, Mickelson spent more than an hour on the practice putting green, trying to get a feel for his new armlock putting method.

“Trying it, we’ll see,” Mickelson said between putts. “Just thought I’d try it.”

Mickelson said he picked up the putter over the weekend and tinkered with it over the past few days here in Memphis. “It felt OK,” he said, “so I thought I’d try it.”

The results were mixed.

He needed 29 putts in the opening round and lost more than a stroke to the field on the greens (-1.308). When asked what he thought about the method, he said he didn’t really know – that it was still too new for him to understand what he liked or didn’t like.

“I’m not sold on it,” he said.

Rock-solid on the greens at the PGA Championship, Mickelson has largely struggled with his putting over the past few years. He ranks 137^th on Tour in strokes gained: putting; it’s his third season in a row outside the top 120.

Though the armlock putting style has gained popularity over the past few years – it’s the method used by Bryson DeChambeau and Will Zalatoris, among many others – Xander Schauffele used it at the U.S. Open and struggled mightily on the greens. He reverted back to his usual method a tournament later, and last week he won gold at the Olympics.

Whether Mickelson use the armlock the rest of the week remains to be seen. He was putting in the work late Thursday afternoon, at least. But he also added this with a smile: “My old (putter) is headed here now.”