Mickelson shot a 3-under 67, birdieing three of his final four holes in windy conditions before a thunderstorm softened up TPC Southwind. It was his first round in the 60s since the third round at the Wells Fargo Championship. He hadn't shot below 70 since.
He missed the cut at The Players Championship and tied for 49th last week in the Memorial following a visit from FBI agents and lingering questions about an insider-trading investigation. Lefty hasn't won in 19 events dating to the Open Championship and is among the players in Tennessee tuning up for Pinehurst.
"I did exactly what I need to do and some momentum that I need heading into the U.S. Open," Mickelson said. "Tomorrow's round, the same thing. Finish strong and play a good round."
Ben Crane's 7-under 63 leads the tournament, which was suspended because of darkness with 60 players unable to finish the round. Peter Malnati shot a 65, and Billy Horschel also was 5 under with two holes left to play.
Retief Goosen and Joe Durant each had a 66.
Crane took advantage of a 3½-hour delay that left nearly perfect scoring conditions with no wind and rain-softened greens. He had five of his seven birdies on his final nine, the last a few minutes before play was suspended because of darkness.
Crane needed only 24 putts for his best round of the season, including a 27-footer for birdie on his final hole at No. 9 with only a handful of people watching because officials closed the course to spectators because of the high winds with the storm.
"We caught a huge break being on this side of the wave," Crane said. "You know this is ideal Memphis weather. It's as good as it gets. It was calm, barely any wind. The greens softened up. We were able to attack some of the pins."
Even with tricky wind Thursday morning, Mickelson, who tied for second at Southwind last year, said his focus on each shot was much better. He's trying to better visualize the shot and curve his irons so that his approach shots land closer to the hole, giving him more tap-in opportunities. Finishing with the three birdies in his final four holes was exactly what he wanted in a round with five birdies and two bogeys.
He hit his approach from 135 yards on the par-4 sixth to 5 feet and rolled in the birdie putt. He left himself longer putts with a 7-footer on the par-3 eighth and an 11-footer on the par-4 ninth, but knocked them in for his strong finish.
"I've been struggling with finishing the round strong," Mickelson said. "I had a good round last week on Thursday and then played poorly. To birdie three of the last four made it a great round. That's exactly what I need to do."
Firm greens made it tough to land balls close, but Goosen credited them with helping him roll in some of his birdie putts. He sunk a couple from 5 feet or closer, but also had a couple birdie putts from 14 feet. Goosen also saved par on No. 7 with a 12-foot putt.
"The greens are as good as greens as you can get," Goosen said. "The greens are rolling close to 13 on the stimpmeter. They are really good. You hit the right putt, they are going to go in."
A seven-time winner on the PGA Tour, Goosen hasn't won on tour since 2009. He has two top-10 finishes this year as he continues his comeback from back surgery in August 2012. He tied for third in Memphis in 2011 and said he really likes the course.
That showed as Goosen, who started on No. 10, birdied four of five holes before making the turn. He finished his round with two more birdies and two bogeys, including one on the par-5 third when his drive landed against a tree and forcing him to chip back into the fairway toward the tee.
"But overall happy with my round," Goosen said. "Nice to get off to a good start and try and hold onto that."
Divots: Robert Garrigus withdrew after hurting his wrist in the 18th fairway. He had a 79 that included three bogeys, a double and an 8 on the par-4 17th.
Information from the Associated Press was used in this report.