The New York Mets have placed catcher Francisco Alvarez on the 10-day injured list with a right thumb UCL sprain.

Alvarez suffered the injury during the Mets’ win over the Seattle Mariners on Sunday night in Williamsport, Pennsylvania, during MLB’s Little League Classic. The severity of the injury is not yet known, but there is some initial concern Alvarez could be out for the rest of the season.

Alvarez stayed in the game after his double in the seventh inning. He did not come out to catch in the eighth inning of the Mets’ 7-3 win over the Mariners in the MLB Little League Classic. Mets manager Carlos Mendoza said Alvarez would return to New York for an MRI.