Ben Harding scored the decisive penalty as Wycombe overcame Colchester in a Carling Cup thriller.
The hosts had gone into a two-goal lead following Scott Donnelly's 18-yard strike and a tap-in from Joel Grant.
The U's hit back with Kayode Odejayi's finish from Michael Rose's cross, and an Ian Henderson rocket from 25 yards.
A Steven Gillespie penalty in extra time for Colchester and a long-range equaliser from Stuart Beavon set the stage for Harding's decisive kick.
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Colchester United manager John Ward told BBC Essex:
"I feel for my team, I think they've done everything possible to win the game.
"From being two goals down, we've handled it well, I've been delighted with the response of the team.
"For 30 minutes going up to half-time, I thought our football was absolutely excellent."
Wycombe manager Gary Waddock told BBC Three Counties Radio:
"The players are very pleased with progressing in to the next round, but they're also very pleased with their performance.
"Early on we lost our way in the first half when Colchester pegged us back but we got ourselves back in to the game in the second-half.
"We improved in that spell against a very good team, and you can tell [Colchester boss] John Ward has put a group of players together who are going to do very well this season."
Wycombe 01 Bull 06 Johnson (Winfield - 112' ) 16 Tunnicliffe 19 McCoy 21 Halls 08 Harding 17 Grant 22 Donnelly (Ibe - 104' ) 30 Harris (Rendell - 80' ) 03 Sandell 20 Beavon Booked Substitutes 13 Ingram 02 Foster 05 Winfield 26 Kewley-Graham 33 Ibe 09 Rendell 29 McClure Colchester United 12 Cousins 03 Rose 04 Okuonghae 06 Heath 20 Wilson 08 O'Toole (James - 75' ) 10 Izzet 22 Wordsworth 07 Vincent (Gillespie - 68' Booked ) 15 Odejayi (Coker - 120' ) 16 Henderson Substitutes 35 Pentney 05 Baldwin 25 White 23 James 24 Coker 27 Duguid 09 Gillespie