KANSAS CITY, KAN. – Minnesota United FC won't head back to Kansas City this season, and likely won't shed any tears over it.

The Loons returned Wednesday for a fourth-round Lamar Hunt U.S. Open Cup match against Sporting Kansas City, only 11 days after being blown out at Children's Mercy Park.

The competition was different, but the result — a decisive 4-0 Sporting KC victory — was the nearly the same.

The loss was a secondary concern for the Loons after the game. Defender Joseph Greenspan left the field on a stretcher and was taken to an area hospital after colliding with Sporting KC's Roger Espinoza.

Training staff tended to Greenspan for 10 minutes. He gave a thumbs-up to the crowd as he was taken off the field. An update on Greenspan's condition wasn't available immediately after the game.

"He's got a neck injury of some description. Obviously we'll know a bit better [Thursday]," Loons coach Adrian Heath said. "When somebody's out that long, and I guess taken off on a stretcher, you're a bit worried. [We'll know more] hopefully tonight, if not, certainly in the morning. Obviously we hope for the best."

For the first 42 minutes, the Loons got what they wanted: a nondescript match that kept KC's potent offense mired in the middle of the field. But the final three minutes of the first half proved disastrous, and told the story.

The home team opened the scoring in the 43rd minute, when Sporting KC defender Ike Opara headed home a corner kick from Graham Zusi.

United goalkeeper Patrick McLain tried to punch the corner kick clear of danger, but the ball went past his hand and onto Opara's waiting forehead.

"To be honest, the set piece killed us,'' midfielder Collin Martin said. "I thought Coach set us up really well in the formation, and we were doing really well. But that one goal killed us."

The Loons were hoping to get to halftime without further damage, but Sporting KC struck again. A rocket from 20 yards got past McLain and caromed hard off the post. The rebound went right to Sporting KC forward Gerso Fernandes, who sneaked in past three stationary Loons defenders and calmly put the ball into an open net.

"We can't clear our lines, and we can't get it out of our box, and it kills us,'' Martin said. "Even then, if we get one back, we're in it, but we didn't."

Martin had that opportunity in the 53rd minute, but his laser from distance thumped off the post and went out of play. Aside from that, United's offense was nearly nonexistent.

The Loons were outshot 19-5, and simply outmanned Wednesday.

"We've got a few internationals away, and we needed to give some players some minutes, and it was evident that they needed it," Heath said. "As the game wore on, we couldn't sustain the physicality that you need to against a team of Kansas City's ability."

• The United announced an exhibition with Mexican top-division team Club Atlas for 7:30 p.m. July 15 at TCF Bank Stadium.