The Spaniard was going for a third consecutive European Tour win at Chapultepec Golf Club and shared the lead at the turn on day four before fading down the stretch to finish two shots behind Patrick Reed.
That he was in contention at all was testament to his resilience and quality after he sat at four over after 27 holes.
He came home in 30 on day two to edge himself into red figures and followed that with the course record and lowest round of his career as the 25 year old posted a third round 61.
The comeback was well and truly on when Rahm made four birdies in his first five holes on Sunday and while he did not get over the line this time, he was confident that he gave it everything he had.
I fight until the end and I'll fight every single shot and that's what I do. That's why I think I'm so consistent. I do care. Obviously I want to win but I also do care about giving my 100 per cent every time
"I've been scoring really well," he said. "I would say golf is not about hitting the golf ball. I could hit the golf ball a lot better than I have this year, I just play and I try to get the most out of it.
"I fight until the end and I'll fight every single shot and that's what I do. That's why I think I'm so consistent. I do care. Obviously I want to win but I also do care about giving my 100 per cent every time.
"If there was one day where I didn't give 100 per cent, I wouldn't be able to live with myself. That's what I do. If I keep doing that, keep doing as much as I can every single shot and every single day, I would call it a success just because I truly did as much as I could.
"I keep putting myself in position, worked on some things in the off-season, so it's getting closer. I need to hit some better shots the way I want to and hopefully they start coming together towards the right time and the right time of the year."