Ryan Cresswell's last-gasp header handed Southend a 2-1 win over AFC Wimbledon in the first round of the Johnstone's Paint Trophy at Roots Hall.
Cresswell, who was pushed forward from defence for the closing stages, rose high to head a left-wing cross from Neil Harris into the bottom corner and hand the Shrimpers a deserved win.
Southend, who hit the woodwork through Gavin Tomlin and Ryan Leonard, had to come from behind to get the victory after Frankie Merrifield had put the Dons ahead in the 39th minute.
The 18-year-old midfielder fired a deflected 14-yard shot past Shrimpers goalkeeper Paul Smith although the visitors were unable to hang on to their lead.
Southend drew level 14 minutes into the second half when Tomlin scored from the penalty spot after Britt Assombalonga had been brought down by George Francomb.