Los Angeles: Daniel Berger fired six birdies in a six-under par 64 on Friday to grab a three-stroke lead midway through the US PGA Tour St Jude Classic, last tuneup before next week’s US Open.

Berger preserved his bogey-free round with a scrambling par at the final hole of TPC Southwind in Memphis, Tennessee.

“You’re never happy when you’re punching out of a bunker and you have another 130 yards left but you just have to do what you have to do,” said Berger, adding that he “hit a nice wedge shot in there and made a nice [eight-foot] putt.”

Berger’s nine-under total of 131 put him three shots in front of Tom Hoge, the overnight co-leader who birdied his last two holes to cap a 69 for sole possession of second place on 134.

Five-time major winner Phil Mickelson, warming up for yet another bid for the US Open title he has never won, carded a 65 to head a group on 135 that also included Brooks Koepka (65) and Dustin Johnson (69).

Berger’s birdies included three in a row at eight, nine and 10, and he added two more at 15 and 16 to pull away from the field.

He hit eight of 14 fairways and 16 of 18 greens in regulation.

It’s the kind of performance he’ll need to challenge in the second major of the year next week at Oakmont — where Berger played a practice round on Monday before heading to Memphis.

Berger called the brawny layout in Pennsylvania “the hardest course I’ve ever played in my life”.

He’ll try to build momentum for the campaign this weekend. “To just know I’m playing well enough to contend is big,” Berger said.

Mickelson, seeking his first victory since the 2013 British Open, equalled his low round of the year with six birdies and one bogey.

Koepka had five birdies without a bogey. Johnson the 2012 St Jude winner, was putting the pressure on Berger until playing the final two holes in three over par, with a bogey at 17 followed by a double-bogey at 18.

The rocky finish helped undo the good work of four birdies and an eagle at the par-five third hole. Johnson won the most recent of his nine US tour titles at Doral last year. His seven top-10s this season include two third place finishes, but he hasn’t been able to get into the winner’s circle.