Jordan Spieth reacts after putting out on the 18th green to win the AT&T Pebble Beach Pro-Am. Pic/PTI

San Francisco: Jordan Spieth fired eight birdies in a seven-under par 65 on Saturday to seize a six-shot lead after three rounds of the weather-disrupted US PGA Tour Pebble Beach National Pro-Am. Spieth, in a three-way tie for the lead with world number one Jason Day and Derek Fathauer when the second round concluded early Saturday, pulled inexorably away with a sparkling effort at Pebble Beach Golf Links, one of three courses in use over the first three rounds of the tournament.