Phil Mickelson said he could not have done any more in the final round at Royal Troon after Henrik Stenson produced a record-breaking performance to deny the American a second Open title.
Having headed into Sunday trailing Stenson by a solitary stroke, Mickelson performed superbly, making four birdies and an eagle in a bogey-free 65.
Yet remarkably, the 2013 Open champion was still beaten by three strokes as Stenson fired 10 birdies on his way to a 63 that secured the Claret Jug and the lowest aggregate total in major history.
"It's probably the best I've played and not won," said Mickelson, a five-time major winner who has now racked up 11 runner-up finishes in golf's premier strokeplay events.
"I don't have a point where I can look back and say, 'I should have done that or had I only done this.' I played a bogey-free round of 65 on the final round of a major, usually that's good enough to do it, and I got beat. I got beat by 10 birdies. It's not like other guys were out there doing the same thing.
"I played what I feel was well enough to win this championship by a number of strokes and yet I got beat by three strokes. I put in my best performance, played close to flawless golf and was beat.
"So it kind of goes both ways. I'm happy with the way I played, but even more disappointed that it wasn't enough because you look back and say, 'what do I need to do?'"
Despite his own disappointment, Mickelson reserved warm praise for Stenson, finally a major champion at the age of 40.
"Gosh, it's disappointing to come in second, but I'm happy for Henrik," added the left-hander.
"He's really a great champion. We've been friends for some time. I've always thought that he is one of the best ball-strikers in the game and that major championships are perfectly suited for him.
"I knew that he would ultimately come through and win. I'm happy that he did. I'm disappointed that it was at my expense."
The battle between Stenson and Mickelson dominated the final day and provided echoes of the legendary 'Duel in the Sun', which saw Tom Watson edge out Jack Nicklaus at Turnberry in 1977 with no other player remotely close.
On this occasion, JB Holmes in third finished 11 shots behind Mickelson, who said: "I don't remember being in a match like that where we've separated ourselves from the field by so many strokes.
"It certainly crossed my mind a little bit out there ... that match when Jack and Tom went head to head there in '77. I certainly was thinking about that.
"I know that I wanted to be more of Tom in that case than Jack, but unfortunately - I understand how it feels [to lose out]. It's bittersweet, I guess."