Spieth seizes six-shot lead at Pebble Beach

Joint leader when the fog-delayed second round was completed earlier in the day, the world number six fired a sparkling seven-under-par 65 on the picturesque Pebble Beach Golf Links, one of three venues being used for this week's event.

Spieth, eyeing his ninth PGA Tour victory, needed no more than one putt on 13 of his 18 holes as he posted a 17-under total of 198 to tighten his grip on the tournament.

Brandt Snedeker, a two-time former champion at Pebble Beach who is also considered one of the best putters in the game, carded a 67 on the same layout to finish the day alone in second at 11 under.

Long-hitting Dustin Johnson, who was grouped with Spieth for the first three rounds, returned a 66 to share third at 10 under with Kelly Kraft (66).

Australian world number one Jason Day had been tied for the lead at the tournament's halfway point with Spieth and Derek Fathauer but dropped five shots in his first six holes at Pebble Beach on the way to a 73 to end the day at seven-under par. (Reporting by Mark Lamport-Stokes in St. Augustine, Florida; Editing by Peter Rutherford)