Reigning Masters champion Jordan Spieth remains in contention as he sits five strokes behind Lingmerth, while Tiger Woods just avoided being cut as he followed up his first-round 73 with a 70.
Overnight leaders Hideki Matsuyama and Bo Van Pelt dropped down to tied fifth and tied 10th respectively after the former hit a 71 and the latter finished with a 72.
Lingmerth began his bogey-free round with a six successive pars before breaking that streak with a hat-trick of birdies from the seventh to the ninth. His birdie on the eighth was most impressive though as he sunk a 27-foot putt.
Following consecutive pars on the 10th and 11th, Lingmerth went on to make four more birdies on the 12th, 14th, 16th and 18th. Just like on his front nine, there was one birdie that stood out amongst the rest as he made a 29-foot putt on the 16th.
Sitting one stroke behind Lingmerth is Jason Dufner, who recorded a second-round 67.
Dufner began on a high as he made a birdie on the 11th before faltering on the very next hole when he registered a double bogey as his second shot went into the water.
However, he recovered from the setback with a birdie on the 13th, an eagle on the par-five 15th and an incredible 201-yard hole-in-one on the par-three 16th with his 6-iron. His luck dipped slightly after that as he made bogey on 17th after missing a four-foot putt.
Following his highly entertaining front nine, Dufner enjoyed a relatively quiet back nine as it only consisted of two birdies on the first and third.
Two strokes behind Lingmerth is England's Andy Sullivan and Ryan Moore, who hit a 64 and 67 respectively.
Defending champion Matsuyama lost his overnight lead as he three birdies and two bogeys during his round of 71. Van Pelt also saw his overnight lead vanish as he carded three birdies and the same number of bogeys in his round of 72.
Spieth found himself tied 16th on the leaderboard after his performance dipped slightly in comparison to his first round.
Spieth's round of two-under par 70 began with a birdie on the first before he went on to make a trio of pars.
All that changed when he sunk a 48-foot putt for eagle on the par-five fifth and consecutive birdies on the seventh and eighth.
However, Spieth's woes began on the back nine as he missed a 16-foot putt on the par-four 10th to record a double bogey. His troubles continued on the 12th when he failed to convert an eight-foot putt, which led to him registering a bogey. But, the 21-year-old managed to recover from those two setbacks by making six pars in a row.
Woods meanwhile just avoided being cut by one stroke as he hit a two-under par 70 just like Spieth.
Woods kicked off his round with consecutive birdies on the first and second before making another one on the fourth to round off a fairly successful front nine.
The former world number one had a much more turbulent back nine as he made a bogey on the 10th after missing a 15-foot putt.
He bounced back with two birdies on the 12th and 14th, which came courtesy of a 29-foot putt. But, following consecutive bogeys on the 16th and 17th, Woods saved himself by finishing with a par on the 18th.