USA coach Jurgen Klinsmann Friday said he's "optimistic" striker Jozy Altidore will return from injury to play Belgium in the World Cup round of 16.

He said Altidore, who trained separately from the squad with some light jogging on Friday, was improving daily from a hamstring injury suffered in the USA's opening game, the 2-1 win over Ghana.

USA qualified for the knock-outs despite Thursday's 1-0 loss to Germany and they will now play Belgium in Salvador on Tuesday.

"We are very optimistic. Every day is a big step forward with Jozy," Klinsmann told reporters at the USA's base camp in Sao Paulo.

"It's 11 days now and it's looking better every day so we're optimistic to have him being part of the Belgium game."

Separately a team spokesman confirmed that midfielder Jermaine Jones suffered a broken nose when he collided with team-mate Alejandro Bedoya during the Germany game.

But Jones is expected to play against Belgium and will not wear a protective facemask. The spokesman said both Jones and Bedoya had not suffered concussion after their clash.