D.C. United forward Eddie Johnson, a three-time league all-star, was left off the provisional 30-man roster for the U.S. World Cup squad. (Nick Wass/AP)

When the U.S. men’s national soccer team gathered in Palo Alto, Calif., Tuesday to begin a two-week training camp for the World Cup, forward Eddie Johnson was conspicuously absent. The three-time MLS all-star was left off the 30-man preliminary roster despite significant contributions during qualifying, leaving his D.C. United coach and teammates puzzled and disappointed.

Johnson has not addressed the decision publicly and was not available to members of the media this week before Saturday night’s game against the Montreal Impact at RFK Stadium. United (4-3-2) is seeking a second consecutive win in its first home game this month. The club last played at RFK Stadium on April 26 in a 4-1 victory over FC Dallas.

“As a locker room we’re upset for him,” United defender and captain Bobby Boswell said. “Guys were hoping for him. We want what’s best for guys. We’re definitely a better team with Eddie on the field, but we also wanted him to go help the national team. We think he could contribute, and he’s a high-level player. It’s just unfortunate. We’re happy to have him, but we’re also upset he didn’t get what he wanted.”

Johnson was the co-leader on the national team with 17 appearances last year, and he scored the goal that put the Americans ahead to stay during a 2-0 win against Mexico in September that secured a seventh straight World Cup berth. Johnson, 30, started four times and came off the bench four times during the 10-game final round of qualifying.

But Johnson’s stock was in decline during the spring; he has gone without a goal in eight games since joining United from Seattle at the end of last year. United’s most prominent acquisition in the winter also wound up apologizing to teammates for comments he made in a story on ­MLSSoccer.com in which he said in Seattle he didn’t have to run as much “because we had better guys that had more quality on the ball.”

The highest-paid player on United nearly ended his scoring rut in last week’s 1-0 win against the Philadelphia Union, D.C.’s first regular season road victory since October 2012. An improper offside call disallowed Johnson’s first-half goal, but he indicated after the game he was not bothered by the scoreless start to the season.

“It’s not the easiest thing to put behind you,” United Coach Ben Olsen said of Johnson’s exclusion from the national team. “Good thing is there’s a pretty easy way to, I think, show that he’s not affected too much by it, and that’s by getting out there this weekend and continuing to do what he’s done for this team, and that’s not necessarily scoring. It’s all the other stuff that has to be there that he’s consistently done for our group. If the goals come, that’s great.”

United is set to face its third straight opponent with one or zero wins. The Impact (1-5-3) does have a victory over FC Edmonton, 4-2, on Wednesday in the Canadian Championship to give it some momentum entering its first MLS match in a week and an encounter with former captain Davy Arnaud. The midfielder spent the past two seasons with Montreal until joining United in exchange for an international roster spot for the 2014 and 2015 seasons.

D.C., meanwhile, embarks on a stretch of three games in seven days. Following the match against Montreal, United hosts the Houston Dynamo on Wednesday before visiting the New England Revolution on Saturday night.

United is in third place in the Eastern Conference with 14 points. Sporting Kansas City and New England both have 17 points but have played one more match than United, which also owns a 2-0 result against the Revolution on April 5 at RFK Stadium.

“It’s cliche, but they’re a better team than what they’ve shown in the points department,” Olsen said of Montreal. “Offensively they’re as dangerous as any team in this league. They can put three on you just like that. They’re also obviously going through some tough times, and it’s important for us to have a good start and make sure we continue their tough times.”