Tim Henman has failed to reach the final of the Qatar Open final following a 7-6 3-6 7-6 defeat to Ivan Ljubicic.
The British number one had looked on course for victory after going 5-3 up in the decisive tie-break.
But a trio of unforced errors and a service winner by Ljubicic ended Henman's nine-match winning streak.
The Croatian now meets France's Nicolas Escude in the final, who earlier defeated Argentina's Agustin Calleri 6-2 6-3.
When asked about compatriot Greg Rusedski's positive test for the banned steroid nandrolone, Henman insisted "I'm not going to get involved in that."
However, he did express his shock at the news.
"It quite surprised me and it's strange that it came up now, but I feel that it is good that it came out in the open and everybody knows his side of the story," he added.
Henman was also left shocked by his on-court performance and was left shaking his head in a contest he repeatedly looked on course to win with ease.
He broke to lead 6-5 in the opening set but let Ljubicic break straight back for a first-set tie-break.
And the Croatian easily took the breaker 7-2.
The Briton found his stride in the second set, going 3-0 clear and rarely looking like conceding his advantage.
It was a similar start in the third set and Ljubicic struggled to keep pace before rain briefly brought both players off court.
When play resumed the pair were evenly matched until the ninth game when Henman had three break-point opportunities. But he let them go begging.
In the tie-break he was more willing to attack and deservedly led 5-3 after two impressive chip-charges.
But with a final berth seemingly within his grasp, the errors crept back into his game and Ljubicic pounced.