Goals from strike duo Pablo Counago and Kevin Lisbie gave Ipswich a 2-1 victory over Colchester in tonight's East Anglian derby.
The front men netted in either half to secure the Championship side a third round place in the Carling Cup for the first time since 2002.
Steven Gillespie netted a late consolation for the League One side after coming on as a substitute.
Ipswich made five changes following Saturday's 2-0 home defeat against Wolves, with holding midfielder Ivan Campo came in for his debut.
Colchester boss Geraint Williams made three changes from Saturday's 3-1 away victory at Swindon.
Ipswich threatened from the outset, with Jonathan Walters heading over from an Alan Quinn corner in the ninth minute.
Colchester, who have not gone past round two since 2004, had their first effort on goal a minute later when Johnnie Jackson's drive from the edge of the box was charged down by Ipswich skipper Gareth McAuley.
Colchester striker Clive Platt blazed over on 15 minutes after outpacing McAuley, who had misjudged the bounce of the ball.
Ipswich, who reverted to their more usual 4-4-2 formation midway through the first half, broke the deadlock soon after when a 25-yard effort from Counago squirmed under the body of visiting goalkeeper Dean Gerken.
Ipswich could have gone further ahead in the 41st minute but Gerken saved brilliantly from Colchester old boy Lisbie's header.
The visitors, buoyed by a 2,500-strong following, started the second half well and went close in the 48th minute when striker Scott Vernon poked a 10-yard effort just wide following a teasing left wing cross from Anthony Wordsworth.
After 51 minutes, winger Mark Yeates beat the wall with his 25-yard free kick but Ipswich goalkeeper Richard Wright saved at the far post.
Ipswich were looking more likely to score and Lisbie, who left Colchester for Ipswich in the summer, shot just wide a minute later after jinking into the box.
Lisbie did make it 2-0 in the 56th minute when the Jamaican striker cut in from the left and curled a shot into the top corner.
The Essex side had a great chance to pull a goal back in the 56th minute but Jackson fired straight at Wright from 12 yards after a scramble in the 18-yard box.
Gillespie went agonisingly close in the 80th minute when Ipswich defender Richard Naylor acrobatically cleared off the line, via the cross bar, after Wright had parried.
But the Us got the consolation they deserved in the 88th minute when Gillespie chipped Wright from the left-hand edge of the box after out-muscling Ipswich's Chris Casement.
Teams
Ipswich Richard Wright, Casement, McAuley, Naylor, Thatcher,Walters, Campo (Miller 76), Trotter, Quinn, Counago,Lisbie (Haynes 73).
Subs Not Used: Supple, Lee, Balkestein, Smith, Rhodes.
Booked: Quinn, Casement.
Goals: Counago 28, Lisbie 56.
Colchester Gerken, Reid, Coyne, Heath, Ifil, Yeates, Jackson,Hammond (Izzet 73), Wordsworth (Perkins 62), Vernon,Platt (Gillespie 62).
Subs Not Used: Cousins, Baldwin, Wasiu, Elito.
Booked: Coyne.
Goals: Gillespie 87.
Att: 17,084
Ref: Richard Beeby (Northamptonshire).
