Murray suffered two breaks of serve in the first set against the third seed and Robredo turned the screw when he picked up another in the opening game of set two. Murray's head dropped as he tamely surrendered another break of serve and was soon 4-0 behind.
The Scot salvaged some pride by holding his next two service games but the Spaniard had little trouble in serving out the match.
In Murray's defence, the conditions were poor in Las Vegas and the youngster struggled to come to terms with the strong winds on court.
"For the last couple of years I've not really played in anything as bad as what it was out there," said Murray.
"I could have played much better but I could have done with slightly calmer conditions after just coming from playing indoors for four weeks.It was not really great for getting into a rhythm and getting used to playing outside again - I even almost missed a couple of serves.”
"But I also wasn't quite all there unfortunately."
