A 22-year-old Bronx man was seriously injured with head trauma after he hopped a fence and was struck by a subway train near Yankee Stadium early today.

The victim _ who may have been trying to retrieve his cell phone _ was found under the sixth car of a northbound No. 4 train between the 149th Street and 161st Street stations about 3 a.m., authorities said.

Police had to cut through a fence to find the man, who was moaning and conscious. The train apparently tried to stop but couldn’t do it in time.

The MTA said No. 4 service was suspended from 149th Street to the Woodlawn station for about an hour.