Andy Murray's recent run of success came to a shuddering halt against Antony Dupuis at the Hall of Fame Championships on Wednesday. The Frenchman, ranked 111 in the world, beat the 18-year-old Scot 6-4 6-1 in Newport, Rhode Island.
Murray's defeat ends the possibility of an all-British quarter-final, with Dupuis going on to face Greg Rusedski.
The British number two, seeded third, beat Robin Vik of the Czech Republic 6-2 7-6 (7-5).
Murray was broken in the final game of the first set against Dupuis and then failed to take any of the three break points he earned at the start of the second.
The Frenchman went on to break three more times on his way to victory in an hour and seven minutes.
Murray, who beat world number 126 Gregory Carraz on Tuesday, admitted he had not enjoyed the Newport grass courts.
"It was good I won that match yesterday, but I didn't learn much today," said the Scot.
"That is the worst type of court for me to play on because the balls stay so low."
Murray now heads to California to play Challenger events in Aptos and Tarzana, followed by two more Challengers in Canada.
Earlier, Wesley Moodie had a 6-4 6-1 win over top seed Taylor Dent.
Second seed Vince Spadea defeated Karol Kucera Slovakia 6-1 6-4, while fifth seed Robby Ginepri lost to Michal Mertinak 6-3 6-4.
Alexander Waske beat Daniele Bracciali, who took Andy Roddick to five sets at Wimbledon, 7-6 (9-7) 7-6 (8-6).
MMIX
E-mail this to a friend 
Printable version 
Dupuis on his day is a very tough opponent