Tim Henman fell at the first hurdle in the Indian Wells Masters Series, beaten 7-5 3-6 7-5 by Czech Jan Hernych.
Henman was playing only his third match of the year
The British number two made a shaky start as he dropped the first set to the world number 73 in California.
But he found his rhythm in the second to level the match, and led 5-4 after two breaks of serve in the third.
But Hernych broke back and then made it 6-5, putting pressure on Henman to hold his serve. He double-faulted at 30-30 to give Hernych match point.
The 32-year-old was playing in only his third match of the year after struggling to shake off injury problems at the start of the season.
Henman made an early exit from last week's ATP event in Las Vegas after winning one round-robin format match but losing his second and he admitted his display against Hernych was frustrating.
"My serving was the area that was having the biggest impact on my game and I struggled with my rhythm," he said.
"I worked hard and got myself into a winning position but then played poorly at the end.
"The biggest positive I can take is that I'm feeling healthy and am physically in good shape so I just need to be a bit more patient with my match play."
Henman will link up with Andy Murray in the men's doubles at Indian Wells as Britain's new Davis Cup captain John Lloyd assesses his options ahead of next month's Euro-African Zone One tie against the Netherlands in Birmingham.
"I'm looking forward to it and the more time I can spend on court at this stage the better, whether it is singles or doubles," said Henman who announced earlier this year he wanted to be considered for Davis Cup selection again.
"It works well for me to get some more matches and it's another chance to try a few different options ahead of the Davis Cup."