Holland's Maarten Lafeber sank 16 birdies and an eagle over two rounds to earn a two-shot lead at the halfway stage of the Portugal Masters.
His 5-under 67 on Friday, which followed an opening 64, took the 35-year-old Dutchman to 13 under. Finland's Mikko Ilonen was in second place at 11-under after a 68.
Lafeber's stack of birdies suggested the record-winning Masters score of 27-under set by England Steve Webster in 2007 could be challenged on Sunday night.
Lafeber, whose only previous win in Europe was in the 2003 Dutch Open, would have led by three had he not dropped a shot at the 17th.
"I lost a bit of focus and ended up in the water," he said. "You have got to be careful out there and not get too greedy. But at the same time you also have to be aggressive because there are so many birdies to be made out there.
"I know that if I don't make any more and end up on the same score I will probably struggle to finish in the top 10."
After sharing the first round lead at 8-under, Lafeber's second round began in some style when at the second he holed a sand wedge from 110 yards out and he immediately followed up with a successful birdie putt on the next green.
Swedish pair Robert Karlsson and Johan Edfors , who like Lafeber had shot 64 on the opening morning, found it hard to keep up the pace playing Friday afternoon in a breeze and on greens made bumpy by heavy traffic.
Karlsson could only shoot a 71, which dropped him back into a share of fifth place, while Edfors was a shot further back in joint 11th place after a level-par 72 .
Following the first day pattern, it was the morning starters who scored lowest, with Portugal's Jose Felipe Lima moving into a share of third place with France's Raphael Jacquelin by shooting an 8-under 64.
Their efforts, however, paled alongside those of Francesco Molinari, the Italian who recently made his European Ryder Cup debut.
After his opening 2-over 74, Molinari was in danger of swapping the glory of victory at Celtic Manor with a missed cut, but he produced 10 birdies in a second-round 62, which was only one shot outside the course record 61 held by Martin Kaymer.