CHARLOTTE, 15 May 2015 (AFP) - Streb, seeking to add a second US tour title to the McGladrey Classic trophy he lifted in October, had seven birdies without a bogey in a morning round that stood up to all afternoon challenges.
Patrick Reed, playing alongside world number one Rory McIlroy, had eight birdies, grabbing a share of the lead before his second bogey of the day at the 17th saw him finish in a tie for second on 66 with Kevin Chappell.
McIlroy ran into even more trouble at 17, where a double bogey halted his bid for a late surge.
"One big mistake," said McIlroy, whose tee shot at the tough par-three hit the rocks in front of the green and deflected into the water.
US veteran Stewart Cink, who has not won since the 2009 British Open, was among a group of five players sharing fourth place on five-under 67.
He was joined by Webb Simpson, Ricky Barnes, Michael Thompson, Chesson Hadley and Billy Hurley.
South Korea's K.J. Choi, Sweden's Carl Pettersson and American Patrick Rodgers were tied on 68, and defending champion J.B. Holmes headed a big group sharing 13th place on three-under 69.
Northern Ireland's McIlroy, who earned his first US PGA Tour victory at this event in 2010, was a stroke further back on 70.
Despite his miscue at the 17th, he said his round overall was satisfactory.
"I did what I wanted to," McIlroy said. "I took advantage of the par fives and made birdie on a couple of par fours."
Streb teed off on the back nine and got up and down for birdie at the par-five 10th.
He rolled in a 19-footer for birdie at 11, then picked up another stroke at the par-five 15th.
Streb's run continued with a 35-foot birdie putt at 17.
He picked up three more strokes coming in, capping his round with pars at eight and nine.
"It's the first time in a while I feel like I have my putter working," Streb said.
Reed responded to an opening bogey with a birdie at the second, then reeled off four birdies in a row starting at the fifth hole to make the turn at four-under.
Birdies at 10, 14 and 15 pulled him level with Streb, but he was in a bunker at the 17th en route to a bogey.
"I felt like coming into this week I haven't really been hitting the tee shots very straight and that's kind of key around here," Reed said.
"Even though I only hit eight fairways, to me that seems like a lot. The putter was working really well, I was making a lot of good putts. I feel like my iron swings were really solid."
Leading first-round scores on Thursday in the US PGA Tour's $7.1 million Wells Fargo Championship (USA unless noted, par-72)
65 - Robert Streb
66 - Patrick Reed, Kevin Chappell
67 - Webb Simpson, Ricky Barnes, Michael Thompson, Stewart Cink, Chesson Hadley, Billy Hurley
68 - K.J. Choi (KOR), Carl Pettersson (SWE), Patrick Rodgers
69 - Matt Jones (AUS), Kevin Streelman, J.B. Holmes, Hideki Matsuyama (JPN), Bill Lunde, Shawn Stefani, Brendan Steele, Steven Alker (NZL), Justin Thomas, Martin Flores, Russell Knox (SCO), Geoff Ogilvy (AUS), Angel Cabrera (ARG), Kevin Kisner, Will MacKenzie, George McNeill, Scott Gutschewski