Brent Kallman sprang into action minutes after Minnesota United made an emergency defensive sub in the first half of Wednesday’s scoreless tie with Houston at TCF Bank Stadium.

Ish Jome had entered to replace injured starter Joe Greenspan, and Kallman corralled Jome on the field to tell him discipline and communication with teammates were necessary to shore up the Loons’ ever-shifting back line.

For Kallman, a Woodbury native who has established himself as a bona fide Major League Soccer center back defender this season, it was the manifestation of him working to become a more vocal team leader. Related Articles Houston Dynamo scores twice in 2nd half to tie Minnesota United

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“It’s a great help for the team,” Jome said Friday. “He is definitely more assertive.”

Kallman will be counted on again as the Loons (5-11-4) have to piece together another defense for their game against the New York Red Bulls (9-8-2) at 3 p.m. Saturday at TCF Bank Stadium.

United will be without regular captain and center back Francisco Calvo, who likely will play for Costa Rica against the U.S. in the Gold Cup semifinals on Saturday night. Jermaine Taylor is with Jamaica for their semifinal against Mexico. Greenspan is out with a concussion and broken nose. Vadim Demidov, who started the season as the Loons’ captain, is away as United tries to find a suitor for the high-priced bust.

New Zealand defender Michael Boxall, who United signed earlier this month, has been in Canada trying to sort out visa-related issues and might not be able to play Saturday. Boxall’s recent play in South Africa, Russia and elsewhere has complicated the application process, United coach Adrian Heath said Friday.

“We are still hopeful and if he gets back in time, then we will have a decision to make and see how he feels,” Heath said.

That means converted outside defender Justin Davis, who filled in to keep the Dynamo off the scoresheet Wednesday, or someone of his ilk likely will start next to Kallman.

Heath said the club missed Kallman when a June 24 knee injury sidelined him for two games. Kallman didn’t play in the first two games of the season, but made 15 consecutive starts from mid-March to late June.

“He’s at that stage now in his career where he’s here on merit,” Heath said. “In the beginning when he just got in the team and you’re just not sure where you stand in the pecking order and everything, it’s a little bit hard to be that leader and to be vocal.”

Heath added: “There are not many that I would change Brent for in this league.”

When Kallman made his MLS debut on March 18, and the Loons earned their first MLS point in a 2-2 draw with Colorado, he was focused on making his play mistake free.

Kallman, 26, continues to focus on being consistent each game and leading by example, but he wants to branch out more, too. “I’m not the most vocal guy all the time,” he said. “That is something I need to keep working on.”