Southend reached the League Two play-off final against Wycombe Wanderers after beating Stevenage on Thursday night - after extra-time.
With the tie level after a 1-1 draw at the Lamex Stadium on Sunday, the Shrimpers knew a home win would see them reach the play-off final at the third time of asking, after two semi-final defeats in the past four seasons.
Southend fans flooded onto the Roots Hall pitch in celebration following the final whistle.
A delighted Southend boss Phil Brown said:
"For Michael Timlin to get that goal...dear me! It emphasised the commitment that was shown to try to win the game. We never do things easy at this place - it doesn't seem that way anyway.
"I have made some big decisions in my life football-wise and that's probably the biggest, Michael Timlin to play.
"On Sunday he went in for that horrific challenge and their captain's laid out. In the 90th minute here he went into another header with a skullcap on - it was just the bravest performance I've seen from an individual in my managerial time."
They meet a Wycombe side that this time last year only avoided dropping out of the League on the final day of the season. Boss Gareth Ainsworth has done a great turnaround given limited resources.
Leading 3-2 after the first leg, the Chairboys ensured their Wembley place with a 2-1 win over Plymouth.
Ainsworth will want to replace his own Wembley memories, having lost to Wycombe as a 21-year-old midfielder for Preston in 1994 - the last time the Chairboys achieved promotion via the play-offs - with positive ones.