Murray double-faulted eight times in the three-set encounter, and the US Open champion believes that played a decisive factor in his exit from the tournament.
After the match, the 25-year-old told reporters: "It was very hot; there were a lot of long rallies.
"Sometimes if your legs are just a little bit tired, you can miss serves. The timing might go off a little bit and you're not quite getting up to them. That's maybe what happened today."
Murray will now head to Miami for the second Masters series tournament of the year.