It looks like the Union's much-improved midfield depth will be tested on Day One of the brand-new season.
The squad returned to training on Tuesday minus two starters, including the club captain and last summer's biggest signing.
The nonattendance of Maurice Edu was not a surprise, but the absence of Tranquillo Barnetta came out of nowhere.
"Mo still hasn't trained with us at all," Curtin said. "Obviously he's a big piece of our team. He's the captain, he's a leader, he's a guy that we always expect big things from."
"It's tough and it's frustrating, but Tranquillo has a little bit of tendinitis in the knee from a former injury," manager Jim Curtin told reporters on Tuesday. "It slowed him a bunch this preseason and he's missed some time. He was able to play 60 minutes versus Montreal but isn't quite fully fit right now. He's still getting himself going."
Barnetta missed most of Bayer Leverkusen's 2011-2012 campaign with that knee injury, which required a second surgery after flaring up in the preseason.
He was the key signing of the summer transfer window and a player tasked with replacing Cristian Maidana's production in the attacking midfield role.
But the Union have plenty of cover in that position. Ilsinho and Roland Alberg can both play in the number ten spot, along with Leo Fernandes and even Chris Pontius if necessary.
The problem is the defensive midfield, where Edu's absence leaves a hole at one of the more important positions on the field.
"Mo still hasn't trained with us at all," Curtin said. "Obviously he's a big piece of our team. He's the captain, he's a leader, he's a guy that we always expect big things from. To not have him is a detriment, but everybody has picked up the slack and has played well. He's looking doubtful, to be honest, for Dallas, but the players in his spot have competed well. Obviously we're a better team with Mo on the field, but the reality is that the game doesn't wait for anybody. We have to move on. It's not likely that he'll be part of the Dallas game."
Edu continues his rehab apart from the team. He's been working on an individual program organized by sports science staffers Garrison Draper and Bill Knowles, and strength and conditioning coach Kevin Miller.
Curtin described the length of the recovery as "frustrating" for everyone.
"It has nothing to do with the surgery he had," Curtin explained. "It's an injury that, it's called a 'stress reaction' and it's in his leg. Nothing's broken or anything like that. Before he's physically cleared to train with us, he has to have that fully heal, and then he can be out there."
Edu's injury seems to have evolved over the past six months.
It began with a partially torn groin that caused him to miss significant time leading up to last year's U.S. Open Cup Final. Edu played in that game, then underwent sports hernia surgery that shut him down for the rest of the season.
It's not clear when this stress reaction surfaced, but it's keeping one of the best players on the team on the shelf.
"These are two guys who, again, are leaders and captain-type players," added Curtin. "They're two guys we miss greatly. It's two important pieces that may or may not be with us in week one, but we have to prepare accordingly."