Playing the final three holes of his second round at the St. Jude Classic on Saturday, Mickelson started with a birdie that dropped him to 5 under, but then went bogey and double bogey on No. 18 for a second straight round.
He finished with an even-par 70 that left him 2-under 138 in his first tournament since announcing his wife has breast cancer.
He is eight strokes behind Brian Gay, whose 66 Friday gave him the clubhouse lead at 10-under 130 when play was suspended because of thunderstorms with 78 players on still on the course.
Robert Allenby finished a 64 on Saturday and was a stroke back. Bryce Molder (63) and Vaughn Taylor (65) were tied at 132.
John Daly made the cut at even par and will play the weekend in his first PGA Tour event since returning from a six-month suspension. That means a temporary restraining order keeping his estranged wife off the course remains in effect through the weekend.
Sergio Garcia (3 over) and defending champ Justin Leonard (5 over) were among those missing the cut.
After completion of the second round on Saturday morning, PGA Tour officials sent the 76 players who made the cut off both tees in threesomes trying to get back on schedule.
The storm brought heavy rains to the TPC Southwind that should help scoring on a course golfers already had found receptive.
Its obviously going to make the golf course a little softer, said Allenby, who lost here in a playoff a year ago.
He ended Friday off a bogey but rebounded Saturday with a birdie on his 18th hole to pull closer to Gay.
Woody Austin (66) was at 133 in a group that included David Toms, the two-time champ here (66). Rich Beem (68) and Loren Roberts (67) were among those at 134.
Officials already had fans heading toward the exits when the horn blew Friday. The timing was good with lightning seen 10 minutes later, and the tornado sirens went off about 40 minutes after the stoppage. Winds blew rain sideways and tossed carts across the grounds with some siding ripped off concession stands.
Mickelson was at 4 under and standing next to his tee ball in the 16th fairway with 210 yards to the par-5 hole. He marked his spot, tossed the ball to his caddie and got a ride off the course on a cart. He walked to his car without commenting.
He started well enough Saturday with a birdie. Then he hit a tee shot into the rough and a two-putt bogey on 17 that he followed up with his second consecutive double bogey on the par-4 18th.
Hundreds of fans followed Mickelson from hole to hole yet again, many wearing pink in support of Mickelson and his wife, Amy.
The star this week is Phil Mickelson, said John Senden, who shot a 66.
Mickelson looked more relaxed a couple days after an emotional news conference, even laughing a couple times during breaks in play Friday. He had three birdies and a bogey before just missing with his putter on the back nine. He is using this event to get back into competition mode, and that may have been why he hit iron instead of driver or a wood off the tee a couple times.
He birdied three of six holes to get to 5 under, and his last birdie came when he mashed his drive 348 yards on the par-4 ninth. He stuck his approach within 5 feet and rolled in another putt for birdie.
His putter failed him as he left a birdie attempt short on No. 11 and had to tap in for par. His second shot into the par-4 No. 12 dropped 12 feet from the cup. His birdie attempt rolled just right of the hole and a couple feet past.
Then Mickelson pushed his drive into the rough, coming up a couple feet short of knee-high weeds. He bogeyed the hole but not because of that drive. He missed a 25-footer for birdie, then lipped out a 3-footer for par when the ball hit the back of the cup.
He laid up again on the par-4 15th and had a short birdie putt he pushed a couple feet past with his frustration starting to show. He had a chance to rebound after a strong drive on the 16th, a good scoring hole. Then came the horn.
For Gay, he is trying to do what he did in Hilton Head in April, when he ran away with a victory by 10 strokes. A win here will get him a ticket to Bethpage Black next week, and he birdied five of his first eight holes and get to 12 under at No. 15 before bogeying his final two holes.
I did pretty good being ahead last time, so I was telling myself on the back nine out there to, I was really trying to push and try to make as many birdies as I could but probably pulled the wrong club on a couple holes coming in, Gay said.
Divots: The second-round stoppage marked the seventh PGA Tour event interrupted by weather this year. Gays 130 total for 36 holes is his personal best on tour. He shot 131 twice, most recently at the 2003 Zurich Classic in New Orleans. Guy Boros, tied for fourth after a 66, needed only nine putts over his final nine holes.