With a suspension, national team call-ups and injuries, United will be without nine players this weekend, six of them starters.
Here's the latest:
Defender Joe Greenspan took part in warm-ups. The center-back had been recovering from a concussion for about two weeks.
Starting goalkeeper John Alvbage, who endured a knee laceration against Atlanta on March 12, was also training separately on the sidelines.
Third-choice goalkeeper Patrick McLain, however, was not at practice, still recovering from a concussion. So temporary addition Billy Heavner trained with new-starter Bobby Shuttleworth.
"John's feeling a lot better after the weekend. I think he gets his stitches out tomorrow," coach Adrian Heath said. "Patrick has still got a little concussion symptoms. Joe joined in today [but with] no physical contact. So we'll see how he is in the next couple of days. But I would think it's probably going to be a bit early for all three this weekend."
The only other missing player because of injury was midfielder Bernardo Anor, who is still on the disabled list with a leg injury.
Center-back Francisco Calvo and midfielders Johan Venegas, Rasmus Schuller and Kevin Molino were all absent on national team duty.
Left-back Justin Davis will also for sure miss the weekend match while serving a red card suspension from the 70th minute of the 2-2 draw at Colorado this past Saturday.
Heath said the club spoke to a few people of "influence," and their advice was to not appeal the red card. The coach, though, has watched the challenge three or four times and still thinks it was a "harsh decision."
"I still disagree. I thought Justin went to play the ball and ... obviously he caught [the opponent on the knee]," Heath said. "But I don't think it was malicious. I don't think there was intent, which is, you know, the rules of the game."
Some good news is that draftee Thomas de Villardi, who had played left-back in preseason for United, sent in his contract to the league on Monday and could make the team for the trip to the New England Revolution at 1 p.m. this Saturday.
Heath said he has an idea in his head of what the lineup will be with the absences. But he only specifically said midfielder Ibson, who was a catalyst as a second-half substitute in Colorado, would play against the Revs.
"We have the players that can fill in those spots," winger Miguel Ibarra, who started for the first time against Colorado, said. "Those players are hungry, and they're going to seize their opportunity. ... I think we're just going to be fine."