Kaymer, who suffered an early exit in the defence of his US Open title at Chambers Bay, found water with his approach to the 15th to card a double bogey, but recovered in style to return a second consecutive 69.
The German nailed a 15-foot putt at the par-four 18th to join Ryder Cup team-mate Victor Dubuisson and first-round joint-leader Rafa Cabrera-Bello on four under, with just eight shots separating a congested leaderboard heading in to the weekend.
Home favourite Dubuisson had held a two-shot lead when he followed a birdie on the fifth by holing his approach to the next from 107 yards for an eagle, but carded three bogeys and one birdie in the last 11 holes in a one-under 70.
“There were two shots I hit on eight and nine that finished in a bad spot and made bogeys there and on this course it can turn really bad, but I made a great par on 10 and nice birdie on 12 and I’m very happy with how I played today,” Dubuisson told Sky Sports 4.
“I’m very excited about the weekend but on this course you can easily make mistakes so I will have to play well again tomorrow.”
First round joint-leader Cabrera-Bello, looking for his fifth consecutive top-20 finish, birdied the 17th to card a one-under 70, while South Africa???s Jaco Van Zyl dropped three strokes from his final two holes to join Francesco Molinari and English trio Tyrrell Hatton, James Morrison and Daniel Brooks one shot off the pace.
Brooks fired six birdies and an eagle on his way to a lowest round of the week 66, while Hatton could???ve held a share of the lead had he not bogeyed his final hole after taking four shots from the edge of the green.
“I’ve been trying to get better with how I deal with shots,” Hatton told Sky Sports 4. “I got a bit flustered on the last there and hit three not-so good chip shots, but it’s a learning curve and I am trying to get better.”
Graeme McDowell’s bid for a third straight French title ended with a second round 77, while Renato Paratore is understood to have broken a European Tour record after completing taking four strokes to complete each of the 18 holes.
The Italian posted three birdies, four bogeys and 11 pars in a one-over 72, while three dropped shots from the final four holes saw Danny Willett card a second round 77 and join Lee Westwood in also missing the cut.??