Jordan Spieth has carded a bogey-free nine-under 63 to storm to the top of the leaderboard at the Farmers Insurance Open.
Spieth claimed a one-shot lead by the end of Friday's second round in La Jolla, California, edging ahead of overnight leader Stewart Cink (one-under 71), while Belgium's Nicolas Colsaerts (five-under 67) moved into third.
After a strong opening round on Torrey Pines north course on Thursday, Cink struggled on the southern 18 in his second round – posting three birdies and two bogeys.
Spieth began on the back nine of the north course and started with a birdie – something he would get used to throughout the round.
The 20-year-old American reached four under for the day by the halfway point before another birdie on the second hole pushed him to five under.
Spieth then notched three consecutive birdies starting on the fourth hole, before one more on the eighth ensured he topped the leaderboard at 10 under with two rounds to play.
Colsaerts did not drop a shot either on Friday, managing to navigate the tricky south course with birdies on the second, sixth, 13th, 14th and 18th holes.
The Belgian moved to eight under overall, a shot behind Cink, and one stroke ahead of Billy Horschel (67 on the northern course) and Marc Leishman (71 on the southern course) of Australia.
Reigning champion Tiger Woods, who has won the Farmers Insurance Open seven times – more than any other player – completed a one-under 71 on the northern course to sit one under in a tie for 50th, seeing him make the cut.