Reigning Masters and US Open champion Jordan Spieth ratcheted up his preparation for next week`s British Open by firing a seven-under-par 64 in Friday`s second round of the PGA John Deere Classic.
While fellow American Justin Thomas followed a 63 with a 67 to seize the overall lead, attention focused on Spieth as he bids to win the first three majors of the year.
World number two Spieth found 10 of 14 fairways and reached 13 of 18 greens in regulation in making six birdies and an eagle against a lone bogey to move into a share of 16th after an opening 71 at the event he won in 2013 to secure a place on the PGA Tour.
"Today was a big day," Spieth said. "I made a huge step forward today based on how I felt yesterday. I wasn`t feeling good about my game. Ultimately, this was a big day for me in my preparation for next week."
Spieth hopes to match Ben Hogan as the only player to win the first three majors of the season in the same year with a victory next week at St. Andrews, a feat that would give him the chance to complete a calendar year sweep of the majors at next month`s PGA Championship.
The 21-year-old American won his first major title in April at the Masters, matching the 72-hole course record at Augusta National set by Tiger Woods in 1997, and followed last month by capturing the US Open, becoming the event`s youngest winner since Bobby Jones in 1923.
Thomas had five birdies against a lone bogey to stand on 12-under 130 for a one-stroke lead over compatriots Tom Gillis and Johnson Wagner at TPC Deere Run. Wagner had the day`s low round with a bogey-free 63 that featured eight birdies.
Wagner stumbled on the back nine last week at the Greenbrier Classic and missed a chance for his first PGA title since 2012.
The US trio of Scott Pinckney, Daniel Summerhays and Will Wilcox shared fourth on 132 with the American pack of Bryce Molder, Spencer Levin, Robert Garrigus and Steve Wheatcroft sharing seventh on 133.
New Zealand`s Steven Alker and Americans Zach Johnson, Luke Guthrie, Steve Stricker and Brian Stuard shared 11th on 134.
Spieth said he was struggling on the practice range Thursday evening and again before Friday`s round.
"I knew I needed to shoot at least 67. I wasn`t taking it for granted," Spieth said. "I was still searching. I couldn`t find any answers."
They started coming on the back nine after Spieth began his round off the 10th tee.
He birdied 14, the par-3 16th, the 18th and first holes to serve notice he was on a roll, then sank a 10-foot eagle putt at the par-5 second.
Spieth followed with birdies at the fifth and par-3 seventh before taking a bogey at eight.
"It`s just repetitions," Spieth said. "I`m getting on-course reps and it`s making a difference."