But Northampton - who beat Liverpool last season - were level when midfielder Ben Tozer slotted home from close range after Arran Lee-Barrett had saved his initial effort.

Paul Turnbull grabbed the winner after Arron Davies saw his low shot blocked.

Gary Johnson's League Two side suffered a blow in the warm-up when striker Adebayo Akinfenwa picked up an injury, with Bas Savage drafted in as a late replacement.

Ipswich knocked the Cobblers out of the competition last season and Paul Jewell opted to rest the majority of the side that defeated Bristol City 3-0 on Saturday, with Aaron Cresswell and Emmanuel-Thomas the only players to keep their place.

His second string looked on track when Emmanuel-Thomas scored his first for the club with a cross-shot which evaded Sam Walker.

But Tozer struck after a neat exchange of passes with Jake Robinson before Turnbull took advantage of poor defending to score and put the Cobblers into round two.

Ipswich Town manager Paul Jewell told BBC Radio Suffolk:

"I'm hugely disappointed that players we've given the opportunity to tonight to stake a claim for a first-team place didn't do as well as they should have done.

"I feel if [Michael] Chopra had been playing tonight we'd have won the game comfortably.

"We're desperately on the look-out for a centre-back, but like with every player we go for, it seems six or seven other clubs are also interested."

Northampton manager Gary Johnson told BBC Radio Northampton:

"The victory is very sweet because I thought we played really good football against a really good football team in Ipswich, who have that tradition.

"I did say I thought we could be part of a good match and as long as we showed commitment I thought our football would come out.

"They got their goal but the lads didn't fade and die and picked it up."

BBC