Altidore sprained his right ankle during a training drill Wednesday and missed Thursday's practice. While X-rays were negative, he underwent treatment Thursday night and Friday morning. He was held out of training Friday and could miss Saturday's game against Australia in Roodepoort, the Americans' last warmup match.
"We all hope Jozy will get better. We think he will," Howard said. "We're not losing sleep over it."
Altidore appeared to be walking without a limp. He sat on the bench during training and watched his teammates.
"He continues to make favorable progress, and his status remains considered day to day," team spokesman Michael Kammarman said.
Altidore, who spent last season at Hull in the English Premier League, is the most experienced American forward despite being just 20. The other forwards are Robbie Findley, Edson Buddle and Herculez Gomez.
"Thankfully, with Jozy, it seems to be just mild," Cherundolo said. "I think he'll be OK in a couple of days."
Findley made the 23-man roster in a surprise to some, but he is prized by coach Bob Bradley because of his speed. He had an impressive second half in last weekend's 2-1 exhibition win over Turkey, helping stretch the defense and open space for Altidore, Landon Donovan and Clint Dempsey.
"It felt good. Whenever you can go out and play like that, it will always help your confidence," Findley said. "It would have been nice to get a goal, too, but I was effective in different ways."
In the last season of his contract with Major League Soccer's Real Salt Lake, he started in the March 3 exhibition loss at the Netherlands.
"I wasn't as comfortable as I wanted to be, but I watched game tape and stuff like that, and learned from that," he said. "Then my teammates told me 'just do what got you here.' You know, be aggressive, go at players and all the rest will come. I went with that as my main focus in that Turkey game."
Altidore entered training camp as the only forward assured a spot in the starting 11. Brian Ching, a 2006 World Cup veteran expected to make the roster, was cut.
Findley might suit the style the 14th-ranked Americans are expected to employ against No. 8 England.
"If we're kind of in a defensive mode and we're playing counterattack, then he's very useful," Cherundolo said. "I think especially in the second half of the Turkey game, everybody got to see why he's effective, not only going forward, but I remember plays where he was chasing down forwards towards our own goal. For a defender to see a forward do that is magic. It really sets the tone for the half for everybody else. There are really then no excuses for any defender or midfielder if a forward is chasing back. So it's very important, and the more open the game gets, I think the easier it is for Robbie to show us his qualities."
Saturday's game will be the first for the U.S. team with the much-criticized adidas Jabulani ball. Although the Americans practiced with it last month, they used Nike balls for home exhibitions against the Czech Republic and Turkey.
"Listen, the ball's tragic. It's no secret. Everyone's said that," Howard said. "There are going to be some crazy goals in this World Cup based on the ball, and none of them are going to be called back."
He is rethinking his strategy.
"A lot of balls that are very comfortable for me to catch on a normal day aren't, and so I just need to kind of figure out, get the ball out of danger," he said. "If I'm not going to hold it, just try and put it in safe areas, and I think that's probably going to be the key for a lot of goalkeepers."
Copyright 2010 by The Associated Press