Hubbard's play was bold to the end, taking on a creek at the par-5 18th and converting his sixth birdie over his final eight holes Thursday to post a seven-under 65 at dark in the storm-delayed opening round.
Hubbard broke out of a six-way tie for the lead that included Tony Finau, among dozens of players hopeful of a win to get into the Masters next week.
He was in the middle of the pack when Hubbard began his remarkable finishing kick on the Oaks course at the TPC San Antonio. He made a 25-foot birdie putt sandwiched between a pair of birdies from the six-foot range. He got up-and-down on the par-5 14th for a fourth straight birdie.
He also hit it tight to six feet for birdie on the par-3 16th. And moments before the horn sounded to stop play, Hubbard drilled a fairway metal from the rough over the winding creek in front of the green about 30 yards short of the flag. He pitched to three feet for his last birdie.
The round was delayed about 90 minutes at the start because of dangerous weather in the area, with 24 players having to complete the round Friday morning. That shouldn't affect the timing of the second round.
Australian Karl Vilips, one of those hoping to make it to Augusta, opened with a four-under 68.
He is tied 15th after making six birdies and two bogeys, which unfortunately came in the last four holes that dropped him down in the field.
Six-time PGA Tour winner Finau has fallen out of the top 100 in the world rankings and is currently not on the list for the Masters next week. The only way for him to qualify now is by winning in Texas.
"I feel like I'm really close to putting together a string of good golf tournaments," Finau said.
"I've had some good days during tournaments, whether that's in the first round, the final round, but I haven't been able to put it all together.
"So I'm off to a good start this week. I'll just be looking to capitalise on three more days of good golf."
He is joined by Andrew Putnam, Steven Fisk, Davis Thompson and Robert MacIntyre, who birdied his last two holes. MacIntyre is the only one in that group who already is in the Masters.
The large group at 67 included some players tuning up for Augusta National, some just hopeful of a tee time.
Tommy Fleetwood, Ludvig Aberg and Maverick McNealy are in the Masters. Among those on the outside is Will Zalatoris, who already has gone through three back surgeries as he tries to play his way back into form.
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