NEW YORK – Toward the end of the first half Thursday, New York City star forward David Villa went down in Minnesota United's box, quite unhappy about a challenge from defender Kevin Venegas.

Moments later, the Loons' Johan Venegas stayed on the ground for a few plays after a separate challenge. When play finally stopped enough for Johan Venegas to recover, Villa came over, and the two went forehead-to-forehead in an intense shouting-and-shoving match.

Was Villa confused between the two Venegases? Did Johan Venegas just feel like having a go at a World Cup winner? Either way, both came out of the encounter with yellow cards.

Depth perception

United has yet another quick turnaround, playing host to Columbus on Tuesday, but the squad likely will be pretty thin.

Starters Francisco Calvo and Johan Venegas will leave from New York on Friday to join the Costa Rica national team for the CONCACAF Gold Cup.

With Calvo gone for the tournament, the center back position is looking thin. Fellow starter Brent Kallman is out because of a right knee injury he picked up in Saturday's match, and United coach Adrian Heath termed him "day-to-day" back on Tuesday. Vadim Demidov (knee) and Joe Greenspan (concussion) also are still out.

That leaves Thursday's fill-in for Kallman, Jermaine Taylor, as the lone standing center back.

Additionally, left back Marc Burch is out until August or September after having bilateral sports hernia surgery, and forward Abu Danladi tweaked his right hamstring.

These have made depth a focus for Heath in MLS' secondary transfer window, which opens July 10.

"We are actively pursuing three or four players to hopefully bring in at the next opportunity that we get there. Now, if we can do it, great. If we can't, we can't," Heath said, adding he is looking at moves both within the league and outside of it. "There's a couple of things we need, strength in depth, stronger than we are at the moment.

"And we need people who are in the team to realize, if I don't play well, somebody's going to take my place. And I don't think we've got that enough in one or two positions."