The biggest names of U.S. soccer filed onto Rhodes Field at the University of Pennsylvania on Monday to begin two days of preparation for the U.S. Gold Cup quarterfinals.

Head coach Bruce Arena made it clear on Sunday that he won't leave a single game to chance in the knockout round. Following an at-times frustrating 3-0 victory over Nicaragua, Arena called in six of the team's top talents to join the roster against El Salvador on Wednesday.

The team added forwards Jozy Altidore and Clint Dempsey, midfielders Michael Bradley and Darlington Nagbe and goalkeeper Tim Howard to the lineup. Arena also brought in Jesse Gonzalez, a 22-year-old goalkeeper who switched his allegiance from Mexico to the U.S. this year.

The six players replaced goalkeepers Brad Guzan and Sean Johnson, midfielders Alejandro Bedoya, Cristian Roldan and Kelyn Rowe, and forward Dom Dwyer.

"We're bringing in some experienced players, players of quality, and that only helps our team," Arena said. "They've come in with a good attitude, they've made a good impression on the team and I'm hopeful that we play our best soccer as we move hopefully from the quarterfinals to the semifinals to the finals."

The addition of the five veterans was always part of Arena's plans for the knockout round. But who the stars would replace remained unclear during the group stage. After captaining the team for two games, Bedoya had always planned to head home immediately after Saturday's match to join his wife, expecting the birth of their second child. But other departures were less predicted, such as Dwyer, who scored two goals in his first three games in an American jersey.

The new lineup adds a wealth of international experience to an otherwise young U.S. squad. Howard is a household name for American fans, defending the U.S. goal in three World Cups and notching 115 caps. Dempsey is one of the team's evergreen offensive leaders, while Bradley scored the first heart-stopping goal against Mexico in the Azteca earlier this year.

Monday's practice was upbeat despite the mid-July heat. With the new additions, Howard believes that the team is well-balanced — filled with youth but tempered by experience and hungry for a chance to prove itself.

"We're driven, we're motivated," Howard said. "We're playing this thing to win. We have one singular focus. We're young and there are guys who are excited to try to win a spot, win a trophy. The vibe of the team is very good."

Following Sunday's announcement, expectations swirled around the new roster, with talk of the Americans becoming a favorite to win the Gold Cup. But both Arena and Howard made it clear that their focus remains on taking one game at a time.

The quarterfinals kick off the do-or-die stage of the tournament for the U.S., starting with Wednesday's game against El Salvador — a team that Arena believes has played "some of the best football of the Gold Cup." El Salvador finished group play with a win, a tie and a 3-1 loss to Mexico.

El Salvador will create an aggressive challenge for the U.S. on Wednesday, and the game is expected to draw a large crowd of Salvadoran fans as well as Americans. While the new roster may be stacked, Arena said, the team's talent won't guarantee anything.

"There are eight favorites to win now," Arena said. "This is one game at a time for everyone. I don't think there are any favorites."