Kevin Molino scored the game-winner as two stoppage-time goals lifted Minnesota United to a 2-1 win over 10-man Sporting Kansas City in Major League Soccer's MLS is Back tournament on Sunday.

Sporting looked set to hang on despite the 74th-minute sending off of goalkeeper Tim Melia, but perseverance paid off for the Loons in the seventh minute of injury time when midfielder Molino collected a ball from Raheem Edwards and fired it past backup goalkeeper Richard Sanchez.

Sanchez was forced into duty when Melia was shown a red card for dragging down Aaron Schoenfeld in the 74th minute, denying an obvious goalscoring opportunity.

Kansas City were up 1-0 at the time thanks to Khiry Shelton's 43rd-minute strike.

But Shelton inadvertently launched Minnesota's comeback with an own-goal in the 92nd, redirecting a free kick from Jan Gregus into his own net.

"I think it was a team effort," said Molino. "They were a man down, they had most of the possession in the game. (We) kept fighting. With a lot of players - other players stepped up and delivered for us."

The match opened Group D action in the World Cup-style tournament that is being played inside a locked down "bubble" at ESPN's Wide World of Sports complex at Disney World in Orlando.

The event marks the return of top-flight football in the United States following a four-month shutdown due to the coronavirus pandemic.

But coronavirus concerns hit the tournament again on Sunday as the morning match between DC United and Toronto FC was postponed until Monday after Saturday tests showed one player with an unconfirmed positive result and another with an inconclusive result.

Further tests on players from both teams Sunday came back negative and MLS said the game would go ahead, with the two players with adverse test results sitting out.

"Major League Soccer will continue to prioritize the health and safety of all participants of the MLS is Back Tournament in making these decisions," the league said in a statement.

It was just the latest setback to hit the tournament. Two clubs -- FC Dallas and Nashville -- were forced to withdraw before a ball had been kicked due to multiple COVID-19 cases.

Los Angeles FC star Carlos Vela, the MLS's reigning MVP, also withdrew from the competition due to coronavirus fears.