Rory McIlroy produced the fast start he had craved as he set about trying to create history in the US Open at Pebble Beach.
All four of McIlroy's previous major titles came after a first round in the 60s and the 30-year-old will hope that sequence continues in California after an opening 68 which left him two shots off the clubhouse lead held by Rickie Fowler, Xander Schauffle and Louis Oosthuizen.
Fellow Irishman Graeme McDowell, who won the 2010 US Open at Pebble Beach, was a shot further back following a flawless 69 which was matched by 2014 champion Martin Kaymer and Spain's Jon Rahm.
However, Shane Lowry had an opening day to forget. The Offaly man had two birdies on his front nine but was three over at the turn after dropping a shot on the second hole and recording double bogeys on 6 and 9. He dropped another shot on 11 before finishing with seven straight pars for a four-over 75.
McIlroy won the 2011 US Open with a record total of 16 under par but was a total of 53 over for his seven subsequent starts and 36 over in the first round alone, the world number three admitting after a third straight missed cut in 2018 that his record was "pathetic".
He could therefore have been forgiven for fearing the worst after starting on the back nine and making a bogey on the 10th after pulling his approach into a bunker, but McIlroy birdied the 13th and then hit a superb tee shot on the par-three 17th to set up another.
After scrambling for a par on the 18th, McIlroy picked up further shots on the second and third and also holed from 15 feet for par on the fifth after duffing his chip from heavy rough just off the green.
Victories in the Bridgestone Invitational and US PGA Championship in 2014 make McIlroy the last player to win a PGA Tour event immediately before winning a major, but no player has ever followed a Tour victory with another at the US Open.
McIlroy can achieve that feat this week following his dominant victory in the RBC Canadian Open, where he closed with rounds of 64 and 61 to win by seven shots - the tournament's biggest winning margin in 67 years.
"I think I did what I wanted to do, which was hit it in the fairways for the most part, hit a lot of greens and when I didn't I was able to get it up and down," McIlroy said.
"I did everything you need to do in a US Open, I stayed patient after I bogeyed the first and played really solid after that so I did what you are supposed to do, make a lot of pars, chip off the birdies when you can and it was a good day's work.
"It's important for everybody (to make a fast start) but especially trying to get my way back to winning these big events it is important. The first two majors this year I shot 73 at Augusta and over par at Bethpage as well and it's so hard to chase, especially when courses are so tough
"To get off to such a good start you are right in the tournament from the start which is a nice position to be in."
"My aim was just to focus hard on the golf course because playing with Dustin (Johnson) and Phil (Mickelson), it would be easy to get caught up in what they were doing," McDowell said.
"Dustin plays a different game - that drive he hit on the last was just outrageous - so I had to focus on dissecting this golf course the way I can do it, and I felt like I did a really good job today. I hit a lot of fairways and hit to the right side of the pin a lot.
"I played fairly mistake-free golf until the last and then managed to clean that up as well. Playing with Phil trying to win the US Open and you see his intensity level, you realise you are not the only guy getting nervous and under pressure.
"Thankfully I wasn't coming here to sight-see, well you always sight-see here, but I was coming here to compete and I am really happy with my general execution today and the way I struck the ball. Three more rounds like that and who knows?"
American Fowler, compatriot Schauffle and South African Louis Oosthuizen. shared the mid-field clubhouse lead on -5.
Fowler is one of the players saddled with the tag of 'best player yet to win a major' after racking up eight top-five finishes, four of them coming in one season in 2014.
Further doubts were raised about his ability to close out tournaments when he looked set to blow a four-shot lead in the final round in Phoenix earlier this season, but the 30-year-old rallied to complete a two-shot win and his opening 65 here contained six birdies and a solitary bogey.