Silvis - Reigning Masters and US Open champion Jordan Spieth eagled twice Saturday in shooting a jaw-dropping 10-under-par 61 to seize the lead in his tuneup event for next week's British Open.
The 21-year-old American prodigy fired six birdies in his lowest career US PGA round to stand on 17-under 196 after 54 holes at the John Deere Classic in Illinois, the event he won two years ago to earn his spot on tour as a teen.
"I've just been trying to roll with the momentum," Spieth said. "It's just incredible. I could never have imagined two years ago sitting here."
Spieth, seeking his fourth victory of the year, will next week try to become the first player since Ben Hogan in 1953 to win the first three majors in a season.
He was only the sixth to win the US Open and Masters in the same year, the first since Tiger Woods in 2002.
New Zealand's Danny Lee, who won his first PGA title last week in a playoff at the Greenbrier Classic, fired a nine-under 62 to stand second on 198, but the South Korean-born Kiwi knew his impressive round was overshadowed by playing partner Spieth.
"Jordan just played magnificent today," Lee said. "I hit it very good. I feel very confident for tomorrow."
On a day when heavy rain kept the leaders from starting until late afternoon, Shawn Stefani fired a 64 to share third on 199 alongside fellow Americans Johnson Wagner and Justin Thomas.
Halfway to an unprecedented calendar-year Grand Slam, Spieth decided to make this event his lone warmup from next week's third major championship of the season at historic St. Andrews in Scotland.
Coming off a Bahamas vacation after his US Open victory last month, Spieth struggled in Thursday's first round but found his form Friday and surged to a second-round 64.
"I think it was just on-course repetitions," Spieth said. "Thursday was rough. For whatever reason just started to pick it up on the range.
"Once you see a couple (putts) go in, that turning point in the middle of the round yesterday, that gave me a lot of confidence. The hole looked a lot bigger from there.
"For me right now it's about having faith on control and impact."
Spieth demonstrated that with an eagle at the par-5 second hole after dropping his 260-yard approach two feet from the cup. He sank a 10-foot birdie putt at the fifth, dropped in another from 25 feet at eight and closed the front nine with a six-foot birdie putt.
On the back side, Spieth dropped a four-foot birdie at 13, then closed with a 12-foot birdie putt at the par-3 16th, an astonishing 106-yard eagle at 17 and an 18-foot birdie putt at 18 to close out an impressive day.
"It held up unbelievably well," Spieth said of his game. "I seem to get some lucky breaks here at the John Deere."
None was bigger than at 17, when his tee shot went left into trees and he blasted out toward the hole into the fairway, then holed out his approach, rolling the ball back into the cup on a shot that he was unhappy with at first.
"It was a couple grooves low but that somehow works out for me at this tournament," Spieth said. "I hit it thin and it goes in."
"His third-shot eagle at 17, that was ridiculous," Lee said.
Zach Johnson, who stands four back of Spieth, was on an adjacent hole and heard the crowd roar for Spieth's eagle at 17, saying it sounded like those elicited by such legends as Jack Nicklaus and Woods.
"I was wondering if it was a double eagle (albatross)," Johnson said. "We talk about Jack roars and Tiger roars but I think that young man has some roars of his own."