Rafael Nadal admitted he struggled to come up with a response to Sam Querrey who was "almost reaching perfection" in their Abierto Mexicano Telcel final.
Nadal suffered a 6-3 7-6 (7-3) defeat to Querrey - the first time he has lost to the American in five meetings - on Saturday, with the world number 40 serving up 19 aces en route to victory.
Querrey overcame Dominic Thiem, David Goffin and Nick Kyrgios to reach the final, where he claimed the ninth ATP World Tour title of his career and first since February 2016.
The American's fierce serve and power from deep in the court proved too much for Nadal to handle, but the Spaniard was keen to look to the positives as he continues his return from a wrist injury.
He said: "Querrey was better and the sport is simple, whoever plays better wins. He played at a very high level, almost reaching perfection.
"I played under a lot of pressure because of his serve and baseline game. They were really fantastic and very aggressive.
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"He left me with very few options, and the few I had he also played good.
"I have to congratulate him. I'm also very happy with my week and my game.
"Reaching the final in two of the three tournaments I have played [this year] is good. If they had told me this would happen in December, I would have signed up."
Next up for Nadal are Masters 1000 events at Indian Wells and Miami, where he feels sure of making further deep runs.
"My plan is to train there [Indian Wells] from Monday," the Spaniard said.
"The preparation has been good. I've had a good week in Acapulco and now I have a few days to continue training and I hope it will help me tighten up some things.
"My confidence is good and I hope to fight at the Masters in Indian Wells and Miami."