CARSON, Calif. –The LA Galaxy always want to win the Lamar Hunt US Open Cup, but they're particularly serious about doing so this year – and better-equipped for the fight.

They enter the United States' oldest soccer competition with a fourth-round game Wednesday night against first-year USL PRO side Arizona United in Peoria, Ariz. (10:30 pm ET, streamed live at ArizonaUnited.com), and they'll likely have the closest thing to their first team in the tournament since Bruce Arena took charge in August 2008.

"If you do the math, for the most part, there's going to be a lot of first-team players," Arena said following Monday morning's training session at StubHub Center. "We'll make some changes, but we're not playing a second team. It's not possible to do with the numbers situation."

Robbie Keane won't be in Arizona – he's slated to return Wednesday from a short break following two friendlies with Ireland's national team – and Arena says he "hasn't decided yet" if Landon Donovan will make the trip, but expect to see several Galaxy regulars on the field.

"I think it's going to look that way, and I know some guys who have been playing some quality minutes for us this year are going to be playing because of 'Los Dos' now," said defender A.J. DeLaGarza, who didn't travel for the Galaxy's Open Cup games the past two seasons, both third-round losses at the Carolina RailHawks, who will be home for the June 25 fourth-round game against Wednesday's winner.

"We don't have a league reserve side [to use in the Open Cup] and we're not in the [CONCACAF] Champions League. I think we're going to take this pretty serious."

Center backs Leonardo and Tommy Meyer have started for the Galaxy in the Open Cup games the past two seasons, and Marcelo Sarvas played in the 2012 games. Gyasi Zardes and Robbie Rogers came off the bench last year. Donovan hasn't made a tournament appearance since 2011, and Keane has never played in the competition.

Four first-team players – forwards Jack McBean and Charlie Rugg, midfielder Rafael Garcia and rookie defender Kyle Venter – are unavailable after making cup appearances for "Los Dos," the USL PRO-based Galaxy II reserve team. A few Dos regulars, including Chandler Hoffman, Raul Mendiola and Oscar Sorto, are not cup-tied.

"There's no question we have a stronger roster," Donovan said. "And we have this [World Cup] break now [in MLS], which is going to impact the way we're going to approach the game. It's not like we're playing a midweek game with [league] games sandwiched around it."

Get more Galaxy headlines at LAGalaxy.com

Although their MLS schedule is crowded the rest of the season, the Galaxy have scheduled just one summer friendly, against Manchester United, and won't have Champions League matches complicating matters. They are better positioned for a decent run as they look to add to Open Cup titles won in 2001 and 2005.

"I think [our approach] is a little bit [different], from a standpoint of timing and a congested schedule," said associate head coach Dave Sarachan, who guided the Chicago Fire to trophies in 2003 and 2006. "We always want to win the Open Cup, but some years it's prevented us from putting together our best units for reasons of scheduling and timing and all the rest.

"I don't think the message or the objective is different. It's a competition for a trophy, and we expect to go far and win it."