Lowery shot a 6-under 64 at the TPC-River Highlands course, as did Brian Davis, Johnson Wagner and Brad Adamonis.
There were 27 players within two shots of the lead.
Lowery captured the AT&T Pebble Beach Pro-Am this season for his third PGA Tour victory.
Among the large group at 66 were Vijay Singh, Stewart Cink and Kenny Perry, a recent winner at The Memorial.
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