Jon Rahm said he felt he had let himself and Spain down after surrendering a four-shot lead in the final round of the Paris Olympics golf on Sunday.
The two-time major champion appeared poised to win Spain's second gold in Paris when he took a commanding advantage with eight holes remaining but ended up not even finishing on the podium.
"I don't remember the last time I played a tournament, and I felt this," said Rahm.
"I don't know what the word is because I not only feel like I let myself down, but to just not get it done for the whole country of Spain, it's a lot more painful than I would like it to be."
Rahm was 20-under par for the tournament when he made his sixth birdie of the day on the 10th hole but followed that with back-to-back bogeys.
A seven on the par-five 14th all but ended his chances of gold, which was secured by Scottie Scheffler on 19 under.
Rahm needed a birdie on the 18th to force a play-off for bronze with Hideki Matsuyama, but he made another bogey to finish tied fifth with Rory McIlroy.
"I've gotten the question: where this tournament would rank in my opinion or what I would think it would feel like to win," he added.
"And I think by losing today, I'm getting a much deeper appreciation of what this tournament means to me than if I had won any medal."
"I'm getting a taste of how much it really mattered. I've been very honoured to represent Spain in many, many different events, and to not get this one done stings quite a bit."