Garrigus shot 6-under 29 on the front side, making birdies on Nos. 1, 3 and 6-9. Six of the front nine holes at CordeValle Golf Club ranked among the top seven toughest in Round 1.
'I had flashes of 59 for a second,' he said, 'and I'm like, alright, idiot, stop thinking.'
His back nine wasn't quite as fruitful, but he collected three birdies to one bogey. His score was one shy of the tournament course record, but two strokes better than his previous low number this year.
'It was an A-plus day,' he said. 'I missed a couple of short eagle putts. Can't really get mad at that when you made a bunch of par putts.'
Garrigus is seeking his second career PGA Tour victory. He captured the now-defunct Children's Miracle Network Classic in 2010.