Justin Walters remained on course for a maiden European Tour title at the ISPS HANDA UK Championship but two-time Major winner Martin Kaymer put himself firmly in contention on day three at The Belfry.
South African Walters, looking to complete a wire-to-wire victory after taking charge with a stunning opening 64, carded a three under par 69 to reach 12 under for the week.
That was two clear of Kaymer, who surged through the field with a thrilling 66, and France's Benjamin Hebert, who signed for a 70.
Walters - who has been a runner-up three times on the European Tour, with two of those results coming in Portugal to keep his card - made a perfect start with a birdie from 20 feet at the first.
A gain at the third was followed by a bogey at the fourth, but Walters pitched to six feet from a bunker at the fifth to swiftly get the shot back.
The 39-year-old gained further shots at the seventh and 14th, either side of a dropped shot on the 11th, to double his overnight advantage.
“I was really impressed with myself to be honest,” said Walters. “I've never been in this position - on a Friday I don't think I've ever led a tournament - but I woke up unusually calm.
“Just wanted to go out there and stick with what I thought. Keep playing aggressively and whatever came my way came my way. I stayed with it, gave myself the best chance of making birdies. For the most part I just wanted to be aggressive and I think that panned out for me today.”
The 33-year-old Hebert, also chasing his first title at this level, lost ground after mixing five birdies with three bogeys.
“It was tough for me because I struggled a lot with my tee shots, especially on the front nine,” he said. “But then I managed my rhythm a little better on the back nine. Also, my putting was pretty solid today so I'm pretty happy.”
Hebert's struggles on the front nine allowed Kaymer to move into a share of second as the German seeks a first European Tour win since his comprehensive U.S. Open victory at Pinehurst.
When Kaymer romped to his second Major title by an eight shot margin, it seemed certain that a deluge of titles would be heading his way in the years to come.
However, the 35-year-old started the week 142nd in the Official World Golf Ranking and having missed his last three cuts.
He improved his chances of making a long overdue return to the winner's circle by mixing three birdies with a single bogey to turn in 34, before holing from 15 feet at the tenth for another gain.
A bogey at the 12th was followed by a run of four birdies in five holes as the former World Number One set a testing clubhouse target which only Hebert and Walters in the final pairing could compete with.
“I was hitting the ball fine the last three days, I just needed one of those days where the putter was good and hot,” said Kaymer. “This was one of those days.
“This is where I feel comfortable (on the European Tour), where I don't need to adjust at all.
“You see all the players and caddies that you have hung out with for the last 15 years. I don't want to say family but it's very close, having as much comfort as possible."
English pair Marcus Armitage and Laurie Canter, Spain's Jorge Campillo and Denmark's Rasmus Højgaard share fourth on seven under par - five shots off the lead and three adrift of Kaymer and Hebert.
