The United States were given an early World Cup wake-up call when they were beaten 4-2 at home by the Czech Republic in their opening warm-up game on Tuesday.
US coach Bob Bradley rested many of his likely starters but gave a run-out to key central defender Oguchi Onyewu, who had been sidelined since a knee operation in October and looked well short of match fitness.
The States, who face England in their World Cup opener on June 12, took the lead in the 17th minute through Maurice Edu but goals from Tomas Sivok (44) and Jan Polak (58) put the Czechs in front.
Substitute Herculez Gomez equalised but a shaky American defence conceded twice more as Martin Fenin (77) and then Tomas Necid (90+2) led the Czechs to victory.
Bradley will reduce his 30-man squad to 23 on Wednesday but were he looking for players to give him a last minute re-think, there would seem little scope for adjustment.
"I think for the most part we had good ideas there were certain things that were on the fence and so we will have some discussions tonight and make some tough decisions," said Bradley.
Midfielder Stuart Holden, another player returning from a lengthy lay-off, created both goals.
His in-swinging free-kick from the left was only flapped at by Czech keeper Petr Cech and allowed Edu to tap in the loose ball. Later, Holden's corner kick was nodded back by defender Clarence Goodson before Gomez headed in at the back post.
Gomez and Brian Ching caused more danger than the first half strike pairing of Eddie Johnson and Edson Buddle and Bradley singled out central defender Clarence Goodson for praise.
"I thought that Clarence Goodson still did a solid job at the back and helped us on some set pieces, that was good to see," he said.
But Bradley's biggest concern will be the condition of AC Milan defender Onyewu who was at fault for the first Czech goal, failing to jump and challenge Sivok for his header.
Onyewu looked awkward at times and not surprisingly, after seven months out, was far from the commanding figure before his injury.
"It is good to see him back on the field. Throughout this period in the camp he is moving better all the time, we will see how he comes out of this game, I think he felt good coming off the field and we will keep working him hard," said Bradley.
The United States also face Slovenia and Algeria in World Cup Group C. Before then, Bradley's team face Turkey in Philadelphia on Saturday and then Australia in Roodepoort, South Africa, on June 5.