Storms caused a suspension of play for 3 hours, 40 minutes and, as a result, only about half the field completed their first rounds. Only three players in the current Top 10 played 18 holes Wednesday.
The first round was to be completed Thursday before second-round play commences.
Larrazabal's 64 included an eagle at the par-5, 545-yard 13th hole and six birdies. It would have been a course record at the Diamond Country Club except players were allowed to place the ball on the fairway because of wet conditions.
Thorbjorn Olesen was second at 7-under after 14 holes. Wil Besseling, having played 13, and Thomas Levet, after 14 holes, were both 6-under. Anthony Wall was alone in fifth at 5-under with five holes left in his first round.
Larrazabal played the second nine at Diamond first Wednesday and opened with a birdie. He backed the eagle at 13 with a birdie at 14 and added birdies at 16 and 18 before the rain delay.
He added back-to-back birdies at 6 and 7 in getting to 8-under.