The four-time major victor tumbled down the leaderboard on Friday after shooting a disappointing 76 to move over par, however, the County Down golfer has fought back to three under par and sits in a tie for 16th place, seven shots off leader Jason Day.
It nearly had to be replaced Saturday, as Peter Uihlein took advantage of softer conditions to shoot a 62 that put him in contention at the Wells Fargo Championship. He remained atop the leaderboard until midday through the round.
Mickelson had a 64, his lowest score of the season.
McIlroy, at three-under 210, had four birdies in a row before also bogeying the last. With his bare feet in the stream and the ball on the bank well above his feet, he hit a full shot to the back of the green for a two-putt par.
That was his only birdie as he struggled with the putter for a second consecutive day. He will be in the final group for the first time in almost four years as he tries to win for the first time since a back injury two years ago. Tiger Woods didn't make up enough ground and was nine back.
Back-to-back birdies at the 14th and 15th followed but he was unable to add another gain which would have seen him equal Rory McIlroy's course record of 61 which he set on the way to victory in 2015. He was nine shots behind.
Day's ascension was paired with a collapse from Peter Malnati, who held the lead through two rounds. Uihlein wound up three shots behind at 7-under 206 and still hasn't won on the PGA Tour. There will be no cut, but only the top 70 and ties in the 144-woman field will win prize money. An eagle on the par-5 10th pushed him to 7-under for the day, and one last pair of birdies on 14 and 15 brought him home in 62.More news: Salah: the Champions League final is not me against Ronaldo
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Compatriot Graeme McDowell had six birdies but a double bogey at the last resulted in a 67 and a two under total.
Tough setups made the back nine harder the first two days than it was on Saturday, and the vulnerable back nine was taken over with low scores by Day and many other players in the third round.
Masters champion Patrick Reed (67) and Augusta National runner-up Rickie Fowler, who four-putted the par-three 17th for a double-bogey in his 68, are both among a group of five on four under. He too started the day at 2 over but he fired a 9 under 62 today.
"If I would have made a few more putts or just putting normal, I would have been up there next to the lead", Woods said.
What made Saturday the most entertaining day was a course setup that led to more birdies and more movement on the leaderboard.
Jason Day was forced to hit a majority of his approach shots from the rough in Saturday's round of the Wells Fargo Championship, but none were in as precarious of a spot as he was in for his final approach shot.