Scotland's Stephen Gallacher continued his bid for only a second European Tour victory in more than 400 starts covering 20 years at the Omega Dubai Desert Classic.
The 38 year old nephew of former Ryder Cup Captain Bernard, whose lone success came in the 2004 Dunhill Links at St Andrews, went to the turn in 31 on the third day at Emirates Golf Club.
Joint runner-up in the event with Lee Westwood last year, Gallacher moved from 11 under par to 15 under and led by a stroke from Dane Thorbjørn Olesen and South Africa's overnight pacesetter Richard Sterne.
Despite driving onto the sand waste area down the second, the former Scottish and European Amateur Champion birdied it and followed it more gains on the long third, fifth and ninth.
Sterne, who began the week with a spectacular 62, bogeyed the first, but came back with birdies at third, eighth and ninth, while Olesen, who tied for second in Abu Dhabi a fortnight ago, had yet to drop a shot in the tournament after 45 holes and grabbed three more birdies.
Playing with Gallacher, England's 22 year old Tommy Fleetwood was another to birdie the third, but paid a heavy price for driving into the rough on the sixth.
His second plugged in the face of a bunker and after only just getting out he three-putted for a double bogey six that dropped from joint third to 13th.
Gallacher's compatriot Chris Doak was bogey-free and 11 under after 42 holes, but went in the lake at the short seventh - Gallacher only just avoided the same fate - and double-bogeyed.
Early clubhouse leader on 13 under was England's Steve Webster, who birdied the last three holes for a 66, while Westwood was only one further back thanks to a 67 that concluded with back-to-back birdies.
Webster, who lost a play-off at the Nelson Mandela Championship presented by ISPS Handa in Durban in December, said: "I was dead patient, made a lot of good swings and then all of a sudden you've had a good day.
"I always take six weeks off at Christmas and get a little bit lazy, but I went to South Africa and got a bit of momentum for the season."
He was in a tie for third with Indian Jeev Milkha Singh, who shared the early lead when he sank a 68 yard pitch for an eagle two on the second and birdied the next.
Westwood, playing his first tournament this year, said: "If I'm being honest it was probably the worst I've played in the three days. Stupid game, isn't it?
"I started missing it left and it's noticeably harder to play out of the rough, but I hit a lot of good iron shots and holed some nice putts."
The Emirates course had been softened by overnight rain and some more came as the leaders entered the back nine.
Gallacher, whose opening 63 matched his lowest round on The European Tour, had the chance to equal or even better that after a fantastic burst on the back nine.
After missing out on birdie at the long tenth he holed from 12 feet at the next, almost twice as far on the 12th and then, off a massive drive down the 550 yard 13th, his eight iron approach hit the flag and stopped less than four feet away.
In went the eagle putt to take him to eight under for the round, 19 under for the event and suddenly a four stroke advantage over Sterne.