Andy Roddick suffered a worrying blow ahead of the US Open as he was dumped out of the Legg Mason Classic at the hands of Gilles Simon.
Frenchman Simon recorded a commanding 6-3 6-3 success over the American in Washington, with second seed Roddick looking way below par.
Simon, seeded 13th at the hardcourt event, moved into the quarter-finals after just 69 minutes as a faltering Roddick managed to get just over 50 percent of his first serves in.
27-year-old Roddick is a three-time winner of the tournament in Washington, but admitted it was a worrying performance so close to the US Open.
"It was just a bad night. I really don't have much of a defence for it," Roddick said. "I really don't feel you can defend it.
"I didn't feel right physically, I didn't feel right mentally. It was just a pretty bad effort.
"I'm a little concerned about that. Feeling lethargic and not all there energy-wise, that's not fun for me. I don't enjoy nights like tonight.
"It could be something simple, maybe a vitamin deficiency. I promise you I'm going to figure this out before I do that again. That's not what I built my reputation around.
"There is a reason that I haven't been playing a lot. It's because I've been playing like crap. I felt I didn't do one thing right tonight. I honestly don't think it would have mattered who I played."
Simon had failed to take a set off Roddick in their last two meetings, but converted three of his five break points to move into the last eight.
"I managed to return his serve today," said Simon. "When he decided to wait (and play from the baseline), I was more consistent than him.
"And when he decided to attack and be more aggressive, he made some mistakes."
In the other games, top-seeded Czech Tomas Berdych suffered a big scare against Andrey Golubev of Kazakhstan before winning 6-3 5-7 7-5.
Third-seeded Fernando Verdasco of Spain defeated American Ryan Sweeting 6-4, 7-5, while Xavier Malisse defied 18 aces by John Isner to beat the American.