Third-seeded Andy Murray, playing in his first tournament since back surgery in late September, was upset by Florian Mayer of Germany 3-6, 6-4, 6-2 at the Qatar Open.
Murray was leading 6-3, 3-0 on Wednesday when the 40th-ranked Mayer started to play more aggressively, going for winners on nearly every shot.
Murray's lead evaporated as he only won three of the last 15 games in the one hour, 51 minute match.
Murray hit 25 winners, but the reigning Wimbledon champion countered that with 37 unforced errors.
The last four times Murray played a tournament during the first week of the new season he captured the title: in 2008 and '09 at Doha, and 2012 and '13 at Brisbane.
Top-seed Rafael Nadal of Spain defeated Germany's Tobias Kamke, Germany 6-3, 6-7, 6-3.
In other results, Germany's Peter Gojowczyk beat compatriot Philipp Kohlschreiber 7-6, 7-6 while eighth-seed Fernando Verdasco of Spain lost to Romania's Victor Hanescu 4-6, 7-6, 6-2.