Ruffels shot a four-under 67 and Vilips a 66 as they try to chase down leader Martin Laird (64), who leads a tight leaderboard by one.
A total of 17 golfers are within four strokes off Laird, who only found out he was in the field on Monday.
Laird has four PGA Tour victories, the last one in Las Vegas in the autumn of 2020. He got in when Andrew Putnam received a special invitation to the PGA Championship next week and withdrew.
Laird has been bouncing between the Korn Ferry Tour and whatever PGA Tour events he can get in, which hasn't been much. His only other start was in the Puerto Rico Open, where he tied for 57th.
"Obviously a huge opportunity," the 43-year-old Laird. "Any time you get to play in a PGA Tour event even at my age is still great.
"It's been fine going back and forth, but it's hard sometimes to jump back and forth because you don't really know where you're going and what run you're going to have."
Aaron Rai and Keita Nakajima, a former No.1 amateur in the world, are at 65.
Laird enjoyed a great run in the opening round at rain-softened Dunes Golf and Beach Club.
That was a product of going to a zero-torque putter, and trusting his first read. It seemed to work as he made eight putts over 10 feet - one short of the record in the ShotLink era.
The winner gets into the PGA Championship if he is not already eligible. That's too far off for Laird to consider after one round, but it's been five years since Laird last played in a major.
Presidents Cup captain Brandt Snedeker is in the large group at 67, including Ruffels.
The brother of LPGA Tour star Gabriela, his round included six birdies and two bogeys. His back-to-back birdies starting on the 15th put him right in contention.
Vilips, who has Brooks Koepa among others as company at three under, enjoyed a bogey-free round with birdies on the 12th, fourth and fifth.
with AAP
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