Wrexham striker Paul Mullin injured in collision with Manchester United goalie Nathan Bishop

Striker Paul Mullin, one of the stars of the "Welcome to Wrexham" docuseries, was injured in a collision with Manchester United goalie Nathan Bishop in a friendly Tuesday night and had to be helped off the field.

Mullin was attempting a header when Bishop challenged him just outside the box in the 11th minute and the two went down. Mullin grabbed his head with his right hand and his left hip with his left hand. He was down for about seven minutes. A stretcher and a cart were sent out and Mullin was surrounded by medical personnel, but he eventually got up and slowly walked off with assistance and an oxygen mask hanging around his neck.

There was no immediate word about the severity of his injury. Bishop was not injured and was booed every time he touched the ball after the collision.

The match at San Diego State's Snapdragon Stadium was the third of four in a U.S. tour by the Welsh team that's owned by actors Ryan Reynolds and Rob McElhenney. Wrexham supporters often sing a song called "Super Paul Mullin." McElhenney was at the match.

Wrexham, the oldest club from Wales, recently earned promotion to English soccer’s fourth tier.

Reporting by The Associated Press.