U.S. coach Jurgen Klinsmann has given the team no word yet on who will replace injured striker Jozy Altidore in Sunday's Group G World Cup match vs. Portugal, said forward Aron Johannsson on Friday.
"Whenever he's ready to let us know who's going to start, then he'll do it," the 23-year-old Icelandic-American said. "We just have to wait until he makes his decision."
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With Altidore out for Sunday's high-stakes match against FIFA's No. 4-ranked team (6 p.m. ET, ESPN/WatchESPN), Johannsson and Chris Wondolowski said Friday that they are ready to step in.
"It's a big loss losing Jozy, he's been playing really well and is in great form but I think our roles are going to stay the same," San Jose Earthquakes standout Wondolowski, who didn't play in the Americans World Cup campaign-opening 2-1 victory against Ghana, told reporters shortly before the team flew to the Amazonian city Manaus, the site of Sunday's game.
"I know for myself and Aron that we're both going to be ready to play at any minute and just looking for the opportunity and making the most of it whenever we get the chance."
Altidore pulled up lame 21 minutes into Monday's win, and was later diagnosed with a left hamstring strain. U.S. Soccer announced Thursday that the 24-year-old would not be available against Portugal, but could return later in the tournament. Altidore told ABC's "Good Morning America" on Friday that there was no timetable for his return.
Johannsson, who plays for Dutch side AZ Alkmaar -- Altidore's ex-employer -- replaced his former club teammate against Ghana but was largely ineffective.
Portugal also comes into the match facing lineup questions.
Fabio Coentrao (groin) and Pepe (suspension) are out. Fellow defender Bruno Alves, striker Hugo Almeida and goalkeeper Rui Patricio are questionable with ailments of their own. So is supertar forward Cristiano Ronaldo (knee), although the U.S. is preparing as if the reigning Ballon d'Or winner will be ready to go.
"We certainly expect that he's going to play," midfielder Michael Bradley said. "A game of this magnitude, of this importance for both teams, you'd always expect that the best players are going to find any way to be on the field."