Rory McIlroy put the controversy over his views on the Olympics firmly behind him to make the ideal start to his bid for a second Open title.
McIlroy withdrew from the Games citing concerns over the Zika virus, but subsequently made it clear where Rio ranks in his priorities - saying he would not even watch the golf on TV, preferring "the stuff that matters."
The 27-year-old believes his career will be judged by the number of major titles he wins and set about trying to make it five after recovering from an unconvincing start at Royal Troon to card four birdies in the space of five holes.
McIlroy had to save par from sand on the first two holes but took advantage of the fourth and sixth, both downwind par fives, before holing from 12 feet for another birdie on the seventh.
The world number four had taken "eight or nine" at the famous Postage Stamp in practice after struggling to get out of a greenside bunker, but had no such problems when it mattered thanks to a superb tee shot to just two feet from the hole.
And things could have got even better on the ninth, where his approach clattered into the pin and finished 15 feet from the hole, from where he was unable to convert the birdie putt.
McIlroy hammers the pin! 🚩
Watch it on Sky Sports The Open. Brought to you by @MasterCardUKJuly 14, 2016
However, at four under par McIlroy was in a share of the lead with American Ryder Cup star Patrick Reed and Korea's Soomin Lee as the real challenge of the back nine began.
Justin Thomas had raced to the turn in 31 but bogeyed the 10th and did well to salvage a double bogey on the 15th after tangling with the gorse, while Kevin Chappell had been four under before running up a triple-bogey eight on the 16th.
The biggest damage was being done by the par-four 11th, which played the hardest hole on the course in the 2004 Open and had yet to yield a single birdie.
The group containing former champions David Duval and Sandy Lyle and British amateur champion Scott Gregory had taken 23 shots between them, with Lyle and Gregory needing seven each to complete the 482-yard par four - flanked by a railway line - and Duval nine.
Royal Troon member Colin Montgomerie, who had hit the opening shot at 6:35am, had three-putted the 11th from short of the green in an eventful level-par 71, the 53-year-old starting with a double-bogey six but then carding five birdies in the space of seven holes from the third.
McIlroy was fortunate to find a good lie in the rough after a wayward drive on the 11th which headed worryingly towards the railway line, and made the most of his good luck to save par by two-putting from 10 yards short of the green.
That was not good enough to retain a share of the lead, however, as Reed birdied the 18th to set the new clubhouse target on five under - a shot ahead of compatriot Thomas, who had also picked up a shot on the last.
"The front nine is definitely scoreable but I felt like I was grinding the entire back nine to salvage pars, bogeys and even double bogeys," Thomas said after a 67 on his Open debut. "So to finish like that with a birdie was nice."
Australia's Matt Jones had matched Reed and Thomas in racing to the turn in 31 to join Reed in a share of the lead, with South Africa's Haydn Porteous just a shot behind after eagles on the fourth and sixth.