Tyrrell Hatton took the lead at the Alfred Dunhill Links Championship after tying the St Andrews Old Course record in the third round on Saturday.
Hatton had been four shots behind leader Ross Fisher at seven under at the midway point but now holds a three-stroke advantage over his English compatriot following a spectacular 10-under-par 62.
The blemish-free round, which featured 10 birdies, was the lowest in Hatton's career as the 24-year-old took a significant step towards a maiden European Tour title.
Hatton made the turn at six under and four further gains on a back nine of 32 gave him a commanding lead over Fisher, who posted a three-under 69 at Carnoustie.
"It's quite clearly the best round I've ever had. I've never actually got to double digits before, either, so very pleased with that," Hatton said.
What a day!-- Tyrrell Hatton (@thatton91) October 8, 2016
My Lowest round ever and to do it on @EuropeanTour at the home of golf makes it even more special!
Looking forward to tomorrow!!
Fisher would have been within a stroke of Hatton if not for bogeys at the third and the 16th.
He is one shot ahead of Joakim Lagergren and Richard Sterne, who each sit at 13 under. Lagergren shot a 69 at St Andrews, while Sterne posted a seven-under 65 on the same course.
Germans Florian Fritsch and Martin Kaymer - looking to shake off the disappointment of losing the Ryder Cup with Europe - each shot 65s at Carnoustie and St Andrews respectively to be within five shots of Hatton.
Scotland's Marc Warren is 11 under, with Danes Soren Kjeldsen and Lasse Jensen a stroke further back.
Alex Noren, who had led after the first round, is one of six players on eight under after a disappointing one-over 73 at St Andrews, his three birdies in vain because of bogeys at the third, fifth, 13th and 14th.
Thomas Pieters, who along with Kaymer missed out on Ryder Cup glory at Hazeltine, was another to endure a disappointing day, replicating Noren's score at St Andrews due in part to a double at the 16th, leaving him 12 shots off the pace.