Marsh was hit by a ball that deflected off the bat of Padres pinch-hitter Luis Rodriguez, who was hitting for pitcher Tim Stauffer.
Marsh was quickly attended to by the Padres training staff, including head trainer Todd Hutcheson.
Marsh remained upright and left the field with the some assistance from Hutchseon.
The game was delayed 13 minutes before it resumed with crew chief Marvin Hudson behind the plate and the Mets leading, 1-0.
Corey Brock is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.