The 32-year-old former world number went down 6-4 6-4 to Frenchman Richard Gasquet in his first round match seven months after undergoing career-saving hip surgery.
The 45 time ATP tour victor, had been offered a wildcard by the United States Tennis Association, but the three-time Grand Slam victor said: "We were hoping to hold a wildcard until nearer the time and see how it feels".
Murray will decide over the next few days whether to play singles in Winston-Salem, in North Carolina next week.
The twice Wimbledon and Olympic champion, who feared in January that his career could be over, surrendered his service in the opening game and came within a point of a 3-0 deficit before rallying to lead 3-2.
The three-time Grand Slam champion fell in five sets to Roberto Bautista Agut in the first round of the 2019 Australian Open. "That's just me not running for a ball, which I did do better at the end of the match". "I thought it (being away) would maybe change my perspective completely on things but I am sitting here disappointed which I think is probably a good thing if i want to get back to playing at a high level".
Murray, after all, was playing a singles match for the first time since undergoing a second knee surgery, which nearly pulled the curtains on his career. He's one of the best at doing that, so I was having to move quite a lot laterally, and I didn't move forward particularly well.
"When he drop-shotted, there was a few times I didn't even run to the ball, didn't react to it, and that's nothing to do with my hip".
He said: "If I would have taken the wild card and then not played, then I would have been getting loads of questions about my hip and, 'Why has he turned it down?"
The Scot has nursed himself back into the game since his return from surgery, playing five doubles tournaments since June.
In the Women's Tennis Association Premier 5 event, 11th seed Latvian Anastasija Sevastova was the most notable casualty, defeated 6-7, 7-6, 4-6 by Russia's Svetlana Kuznetsova. Kyrgios will face eighth-seeded Karen Khachanov.
The three-time Grand Slam victor announced his decision after losing 6-3, 6-3 at the Cincinnati Masters first round to Richard Gasquet.
Earlier Marin Cilic of Croatia became the first seed to fall when the 14th was eliminated by Radu Albot of Moldova 6-4 7-6 (6) and Serbia's Miomir Kecmanovic upset Canadian Felix Auger Aliassime 6-3 6-3.