Jimmy Walker shot an excellent opening 65 to set the clubhouse target on day one of the US PGA Championship, but Ross Fisher was hot on his heels at Baltusrol Golf Club.
The players were faced with high temperatures on day one in New Jersey but it proved no problem for Walker, who dropped a single shot in equalling his best round at a Major Championship.
His five under total gave him a one-shot lead over Fisher and Argentinian Emiliano Grillo, with Andy Sullivan in the group a shot further back.
Walker won four events in 15 months between January 2014 and March 2015, with three top tens in Major Championships also helping him seal a place in the 2014 United States Ryder Cup Team.
The 37 year old has gone off the boil a little since but was in fine form on Thursday with gains on the 13th, 15th, 16th, 18th and first. He needed just 25 putts all day and holed a 30-footer for birdie on the seventh to bounce back from his only dropped stroke on the sixth.
Five-time European Tour winner Fisher's best Major finish was fifth in the 2009 US Open and he will have been encouraged by his fine start in Springfield.
The Englishman turned in 33 but took advantage of the unique pair of closing par fives to catapult himself up the leaderboard and record his lowest round in a Major at the 69th attempt.
Grillo turned in 31 and at one point shared the lead with Walker but dropped a shot on the tenth before fighting back with consecutive birdies on the 14th and 15th.
Sullivan won three times on the European Tour last season and a fantastic finish to his round moved him right into contention. After starting on the tenth, the Englishman was level par as he stood on the sixth tee but he made birdies the sixth, seventh and ninth to join American duo Harris English and James Hahn at three under.
Big-hitting Australian Scott Hend was a further shot back after a hat-trick of birdies from the 13th catapulted him up the leaderboard and he was in a group alongside defending champion Jason Day, Swede David Lingmerth and World Number Seven Rickie Fowler.
Welshman Bradley Dredge was playing his first Major since 2010 but looked right at home carding a 69, a score he shared with countryman Jamie Donaldson, Grégory Bourdy, Victor Dubuisson, Lee Westwood and Chris Wood.
Branden Grace and Søren Kjeldsen were then among those at level par.
Two-time champion and World Number Four Rory McIlroy shot his first ever birdie-free round at the US PGA Championship as he signed for a four over par 74.
