UPDATE: At 3 p.m. ET, about one hour before the start of the match, the USMNT posted its starting XI to Twitter. Neither Jozy Altidore nor Kyle Beckerman are starting, but both are listed as reserves. It was unclear how Jurgen Klinsmann planned to use Altidore, but it seems as though the striker will come in later on to provide the Americans with fresh legs.

Jozy Altidore is going to play Tuesday against Belgium in the 2014 World Cup Round of 16, but the extent of his participation is unclear.

U.S. Men's National Soccer Team (USMNT) coach Jurgen Klinsmann said in a pre-match news conference that Altidore was medically cleared to play. That does not mean he will start and play all 90 minutes, in fact, the coach said he did not know how much Altidore will play.

"We don't know how much [he can play] ... but he's available," Klinsmann told reporters in Salvador, according to ESPN. "It's now difficult to say how many minutes.

"We are very optimistic. Every day is a big step forward with Jozy."

In the USMNT's opening match against Ghana, a 2-1 victory, Altidore was chasing down a ball in the corner when he suddenly grabbed his hamstring and fell to the ground in pain. The strained muscle has kept the striker out of his team's draw with Portugal and loss to Germany.

Though Altidore has proven himself a talented goal-scorer, the USMNT managed to make its way out of the first round despite the fierce competition in Group G.

Altidore re-joined the USMNT Monday for a workout in Salvador, though he spent time jogging on his own, in addition to the team activities. Klinsmann may choose to use Altidore off the bench and play the striker later in the match to put fresh legs on the field in the event of a close contest.

Thus far, every game the U.S. has played in have been decided by no more than one goal and Klinsmann has made some key substitutions that have led to big plays. Against Ghana, John Brooks came in shortly before putting a header past the Ghanaian goalkeeper for the winning score.

Against Portugal, Klinsmann put the young speedster DeAndre Yedlin in and he helped facilitate a go-ahead goal late. Unfortunately for the USMNT, Portugal tied the game up about as late as stoppage time allowed.

Klinsmann has not alluded to how Altidore will be used against Belgium, but so far it does not sound like the striker is healthy enough to play all 90 minutes. Also, the last thing Klinsmann needs is for Altidore to exacerbate the injury.