Robert MacIntyre believes his runner-up finish at last month's U.S. Open proved he has what it takes to win a major, as he prepares to try again at The Open.

MacIntyre finished two shots behind first-time major winner J.J. Spaun at Oakmont in Pennsylvania, having gained four strokes on the leader in the final round.

His previous best major finish had come on his debut at The Open in 2019, when he finished tied for sixth at Royal Portrush – the site of this week's tournament.

MacIntyre missed the cut at the Masters to kickstart his 2025 major season, then was tied for 47th at the PGA Championship, but he believes his U.S. Open campaign gave him newfound belief in his abilities.

"I now know that I can win one of these," MacIntyre told BBC Sport.

"Before, I thought I could, but I'd never shown anything that had shown that I could. Yes, I've had a few top 10s in majors, but I was never there over the final few holes.

"Oakmont was the first time I'd had that feeling. On the 16th, I was thinking 'I can do this, it's here for the taking'.

"I thought I played beautifully and it's just knowing that it's there. Okay, it didn't happen, but it's knowing we've got that in the locker when I need it."

Introducing the bag this week @theopen pic.twitter.com/A2fO7vnDcj
— Robert MacIntyre (@robert1lefty) July 16, 2025

MacIntyre outshot Spaun by four strokes over the weekend at Oakmont, but the American's five-under opening round of 66 ultimately helped him fend off the Scot.

"Things were happening that were completely new to me. It was different, but I was expecting it," MacIntyre reflected.

"Yes, there were nerves, but it was exciting. You're shaking, feeling sick. I played the last three holes in one under par feeling like that.

"If the cards had fallen my way, I'd have won the US Open, but J.J. was better than me over 72 holes.

"It was close and we pitch up here with the same thought of trying to win The Open. It makes me really think I can win a major. It's a reality, not just a dream."

MacIntyre, who claimed his first two wins on the PGA Tour last year, will play his opening two rounds alongside Justin Rose and Bryson DeChambeau.