American trio Jordan Spieth, Brooks Koepka and Matt Kuchar fired themselves into contention at The Open by carding five-under-par 65s to share a three-way tie for the lead at Royal Birkdale.
Former world No1 Spieth and Kuchar both hit bogie-free rounds while Koepka, who is bidding for back-to-back Majors following his US Open success last month, countered his one blemish at the 16th with an eagle at the next hole.
England’s Paul Casey, who celebrates his 40th birthday on Friday, trailed the leading pack by a single stroke following an opening round of 66.
Casey, who has concentrated solely on the PGA Tour since 2014, has promised Europe captain Thomas Bjorn that he will make himself available for next year’s Ryder Cup should he lift the Claret Jug this week.
Ryder Cup star Ian Poulter returned his best opening round at a Major – a three-under par 67 – to be tied sixth alongside fellow countryman Richard Bland, who is playing his first Open Championship since failing to make the cut in 1998.
Four-time Major winner Rory McIlroy recovered from a disastrous front nine, during which he carded five bogeys in the first six holes, to fire four birdies on his return to the clubhouse and finish with a one-over 71.
“I am proud of myself for hanging in there, staying as positive as I could and I’m right back in the tournament,” said McIlroy.
“It shows how fickle golf can be. I feel like I have found something out here these last 12 holes and I have to try and go with it for the rest of the week.”
Like McIlroy, world No1 Dustin Johnson carded a 71, as did Olympic champion Justin Rose, who won the silver medal for best amateur at Birkdale in 1998, and fellow Englishmen Lee Westwood and Danny Willett.
Sergio Garcia, meanwhile, who won the Masters in April, was a further two shots behind after a three-over-par 73.
Successive birdies for Garcia at the 17th and 18th holes repaired the damage caused by a double bogey at 16, although his fellow Spaniards Rafael Cabrera Bello and Jon Rahm fared much better on the Southport links course.
Cabrera Bello, fresh from winning the Aberdeen Asset Management Scottish Open at the weekend, was tied for sixth after firing a three-under 67.
World No8 Rahm was one under, as was defending champion Henrik Stenson, Australia’s Jason Day and English duo Andrew Johnston and Matthew Fitzpatrick. Home favourite Tommy Fleetwood finished six-over par.