"I tried to stay super patient," Vegas told Golf Channel. "I knew I was going to hit a lot of bad shots and had to find a way to get a lot of up-and-downs. Staying patient was the key."
Sixty players had yet to start the second round, including Sam Saunders. The grandson of the late Arnold Palmer had fired an opening seven-under 64 to set the pace on Thursday in his quest for a maiden PGA Tour win in his 79th start.
Australian Cameron Percy (71) was the clubhouse leader at five-under 137, with Spieth also five-under after 16 holes.
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Spieth, coming off a commanding four-stroke victory at Pebble Beach on Sunday, continued his sizzling form down the California coast.
"Last week actually was great prep for it because we played through conditions like this in the first round," said the two-times major champion.
"Things aren't always going to go your way on a day like today ... so try and pick your spots on the easy holes and from there hit putts at the right speed and make it as stress-free as possible."
U.S. Open champion Dustin Johnson, who shot a five-under 66 on Thursday, was left cooling his heels in the clubhouse, yet to start the second round.
Australian Jason Day, whose hold on world number one is being threatened this week by Johnson, stood two-under through 15 holes.
Hideki Matsuyama of Japan, who also entered the event with a mathematical chance of supplanting Day, was three-over for the tournament after 15 holes.
He appears headed for a missed cut, along with last year's winner Bubba Watson, who soared to eight-over through 16.
Officials hoped to resume play on Saturday at 7 A.M. (1500 GMT) on the rain-drenched course where high winds had toppled some trees and turned umbrellas inside-out during Friday's play.
(Reporting by Larry Fine in New York; Editing by Andrew Both)
