Wil Besseling made it 36 bogey free holes to lead the way into the weekend at the 2021 Acciona Open de España presented by Madrid but World Number One Jon Rahm was just one shot back in the Spanish capital.
The Dutchman followed an opening 64 with a 65 at Club de Campo Villa de Madrid to get to 13 under and he will face the biggest day of his career in the final group on day three.
Rahm carded a 67 as he looks for a third consecutive win at his home open and, with the weekend entirely sold out, the leading duo will take a bumper crowd round with them in the Spanish sun.
Home favourite Adri Arnaus, England's Ross McGowan and India's Shubhankar Sharma were at 11 under, a shot clear of another Spaniard in Rafa Cabrera Bello, Scotland's Grant Forrest and Frenchman Julien Guerrier.
Besseling was a European Challenge Tour graduate in 2008 and came through the Qualifying School in 2011 but never managed to finish in the top 100 on the Race to Dubai until last season when he secured three top threes.
A tie for fourth at the Austrian Golf Open is his best finish so far this season and he will now go in search of a first European Tour victory.
"The last couple of seasons have been really good," he said. "I did struggle before that so it is good to be out here performing well and making putts, and being on top of the leaderboard after 36 holes, hopefully it will stay that way come Sunday.
"I made some big changes, my caddie is a big support, obviously the family and home and my sponsors that always believed in me, and a new coach that really got me going. So finding the right people around me has really helped and gives me a good feeling and support.
"You still need to hit the ball and get the practice hours in, but we do it all together, and the last couple of years has been really good."
Besseling played a smart up-and-down on the seventh for a first birdie of the day and then put a tee shot to four feet on the ninth to turn in 34.
A 15 footer on the tenth made it back to back birdies before he put an approach to eight feet at the 12th, made two putts from just off the green at the par five 12th and holed a ten footer on the 16th to set the target.
Rahm is looking to emulate the great Seve Ballesteros as a three time winner of this event in the European Tour era, while a victory would also see him boost his chances of winning a second Harry Vardon Trophy in Dubai next month.
The U.S. Open Champion put an approach to five feet at the second and a tee shot to similar range at the ninth to edge closer but he was not at his brilliant best as he turned in 34.
An eagle for the second day in a row from 18 feet at the 14th brought a huge cheer from the crowd and a fist pumping celebration but the 26-year-old found sand off the tee at the 16th to give a shot back.
He then went for the green at the par four 18th but sent his tee shot a long way left, following that with a stunning second to set up a closing birdie from close range and move to 12 under.
"You didn’t see ten under today because of the firmness of the course," he said. "As it gets firmer, it is going to be a more demanding golf course obviously, more challenging and a much more fun golf course to play."
On the fans, he added: "They are all so golf hungry and that is great, I love playing in front of them. You can tell a lot of people here are not golfers and I don’t know how often that happens in the world of golf that people travel a long way to come and watch, so it’s great fun."
Overnight leader McGowan had quickly caught Besseling at the summit thanks to brilliant iron shots at the tenth, 12th and 13th but a lost ball off the tee at the sixth led to a triple bogey before he birdied the par five seventh in a 70.
Arnaus has hit just eight fairways over the first two days but he was still able to card a bogey free 64 in the second round and match his lowest European Tour score with gains on the 13th, 16th, 18th, fourth, fifth, sixth and ninth.
Sharma turned in 35 with an eagle, a birdie and two bogeys but picked up shots on the tenth, 12th, 14th and 17th before eagling the par four last to come home in 29 and sign for a 64.
Cabrera Bello carded a 65, one shot better than Guerrier and two better than Forrest, with England's Matthew Jordan, Spaniard Pablo Larrazábal and Scot Marc Warren at nine under.
