Tsonga was wildly erratic in his 6-4 1-6 6-1 6-3 loss to 52nd-ranked Martin Klizan of Slovakia in Louis Armstrong Stadium.
"It seemed like I couldn't hit the ball hard enough to put my opponent out of position," said Tsonga.
"I don't really know why it was like this today, but sometimes it happens with me. I don't know.
"It's tennis. I will tell you that. We have to play every week. I'm not a machine. Sometimes I'm tired. Sometimes not. Sometimes in good shape. Sometimes not. That's it."
In Image: Jo-Wilfried Tsonga of France jumps over the net during his match against Slovakia's Martin Klizan