Bryan played 26 holes in 10 under Friday at TPC Deere Run, birdieing three of the final holes to finish off a first-round 66 and shooting a 64 in the second round to reach 12-under 130.
''Been hitting the ball great all week, really the last couple weeks,'' Bryan said. ''Struck it well, made the putts when I needed to, and here we are.''
Area favorite Zach Johnson faced a long day Saturday after not even getting onto the course Friday.
Play resumed five hours late at noon after nearly 2.4 inches of rain overnight - on top of the inch Thursday morning that delayed play 3 1/2 hours Thursday morning and afternoon. Because of the wet conditions, the players were allowed use preferred lies in the fairways in the second round.
Bryan has made a fast rise since focusing on tournament golf last year after working as a trick-shot artist with brother George. The 26-year-old former South Carolina player dominated the Web.com Tour this season, winning in Louisiana, Mexico and Kansas and earning $449,392 in 13 starts.
''Just knowing that I've been in contention and been able to hit the shots that I needed to on that level, I mean, there's a lot of really good players out there, and it's just as hard to win a golf tournament out there as it is out here, I presume,'' Bryan said. ''Just knowing that I've been there and been able to hit the shots under pressure, I think should help me out moving forward.''
In his bogey-free second round that began on No. 10, Bryan birdied five of the last seven holes in the on his opening nine, and added birdies on the par-5 second and par-3 seventh.
''The second round I was able to fire at a lot more flags just because we had ball in hand,'' Bryan said. ''The course is not really that long, so got a lot of short and mid-irons into these greens, and the ball is just hitting and stopping, you don't really have to worry about it spinning back too much.
''They're soft enough to where they're just kind of hitting and reacting, really, really soft. So was able to fire at a few more flags that maybe I wouldn't have normally gone after.''
Steve Marino was a stroke back after rounds of 66 and 65.
''I'm happy to be done,'' Marino said. ''Can't wait to get out of this shirt. It's just so humid out there. ... I played really well today. I played really well yesterday. Finally, feel like I'm starting to come around. It's been a struggle all year. It's nice to kind of see things coming together.''
Johnson opened with a 65 on Thursday. The 2012 tournament winner and two-time major champion is from nearby Cedar Rapids, Iowa.
Playing partner Steve Stricker had a 70 on Thursday. The 49-year-old Stricker, a former University of Illinois player from Wisconsin, won the event in 2009, 2010 and 2011.
NCAA champion Aaron Wise was 3 under overall with three holes left. Making his PGA Tour debut as a pro, the former Oregon player won a PGA Tour Canada event two weeks ago in Edmonton, Alberta.
Jordan Spieth chose not to defend his title because he didn't think it would be appropriate in light of his decision to skip the Rio Olympics.