Whitley Bay, League Cup Finalists last season, crashed out of the competition in the second round on Tuesday night.
An under-strength side because of injuries was dealt a severe blow after 28 minutes when defender Craig Smith fell awkwardly after challenging for a high ball and had to be taken to hospital.
Whitley had to reorganise their defence with Josh Day coming off the bench to replace Smith.
Seaham took the lead after 37 minutes but Michael Laws gave the Bay hope when he equalised on the stroke of half-time.
After the interval the Second Division promotion favourites took charge with Bay’s makeshift defence struggling to cope and with former Bay legend Lee Kerr controlling the game from midfield, the hosts scored at regular intervals and it was in the final minute of the game when Paul Chow got Whitley’s second goal.