Tennessee - Ben Crane, seeking his first US PGA triumph since 2011, fired a five-under par 65 on Friday to seize a six-stroke lead at the storm-hit $5.8 million St. Jude Classic.
The 38-year-old American made six birdies before closing with his only bogey of the round to finish 36 holes on 12-under 128.
Only 32 players completed their second rounds at the TPC Southwind before play was halted for the day after hours of thunderstorms.
Organizers of the tournament, which was also delayed by inclement weather on Thursday, hope to resume Saturday morning.
Crane's nearest pursuers on the course were Sweden's Carl Pettersson and American Jason Bohn, each on six-under. Pettersson had one hole to complete and Bohn two.
Davis Love and Billy Horschel, Crane's closest rivals in the clubhouse, were another stroke adrift on 135. Love shot 70 after finishing an opening-round 65 Friday morning. Horschel shot 68 in the second round.
Also on five-under was American Peter Malnati, who had yet to start his second round.
Crane sank a 44-foot birdie effort at the first hole, added a 22-foot birdie putt at the seventh hole and put his approach at the ninth to three feet to set up another birdie at the turn.
Crane followed with a 14-foot birdie putt at the par-3 11th, a 10-foot birdie putt at 13 and an eight-foot birdie putt at the par-5 16th.
But at 18, Crane found a fairway bunker and missed a seven foot par putt for his first bogey of the event.
"I certainly didn't expect to be here," Crane said of his spot atop the leaderboard. "If someone would have told me a couple days ago I would be standing in front of a bunch of cameras, I would have asked, 'What did I do?'"
With only one top-25 showing in 16 events his season, Crane has struggled but found form after changing his swing to ease pain in his back.
"It has been a really, really hard year," Crane said. "You start wondering, 'Am I going to get it back?'"
It was when he needed treatment at the Humana Challenge in January that he knew he needed to make a change.
Crane seeks his fifth US PGA career victory, the first since the 2011 McGladrey Classic.
"It's fun to be nervous," Crane said. "It's fun to be in the competition and compete."
Reigning British Open champion Phil Mickelson, who will try to complete a career grand slam by winning next week's US Open at Pinehurst, was on three-under. The 43-year-old US left-hander had yet to begin his second round.
Leading scores on Saturday after completion of the storm-interrupted second round of the US PGA St. Jude Classic (par 70, USA unless noted):
128 - Ben Crane 63-65
132 - Retief Goosen (RSA) 66-66, Camilo Villegas (COL) 68-64
133 - Peter Malnati 65-68, Troy Merritt 67-66
134 - Carl Pettersson (SWE) 67-67, Brian Harman 69-65
135 - Davis Love 65-70, Billy Horschel 67-68, Jason Bohn 67-68, Padraig Harrington (IRL) 68-67, Phil Mickelson 67-68, Dustin Johnson 68-67, Ted Potter 68-67, Andrew Svoboda 69-66
136 - J.J. Henry 66-70, Chesson Hadley 67-69, Tim Wilkinson (NZL) 68-68, Ben Martin 69-67, Stewart Cink 70-66