Alan Lee's second-half penalty ensured Ipswich a safe passage into the FA Cup fifth round at the expense of giant-killers Swansea.

The Town striker broke the deadlock from the spot in the 64th minute but Swansea, riding high in League One, matched the Tractor Boys for long periods.

Ultimately, however, Kenny Jackett's men bowed out with their with their pride intact and reputation enhanced after dumping Sheffield United 3-0 out in the previous round.

The Swans received a boost prior to kick-off when Thomas Butler overcame a hip injury picked up in Tuesday night's 2-0 win over Gillingham.

Butler struck twice in the previous round's win at Bramall Lane to help fire Swansea into the last 32 and set up the clash with the Tractor Boys.

Swansea defender Izzy Iriekpen found himself in unfamiliar territory inside the second minute when he hit a fierce shot from 18 yards which required a fine block from Gavin Williams.

Swans striker Adebayo Akinfenwa then found space to curl a neat right-foot shot just wide of the far post.

Ipswich, however, soon established a firm foothold on the game and a steady stream of crosses by Jaime Peters led to several nervous moments in the visitors' ranks.

Town midfielder Billy Clarke hit a superb left-foot shot from 18 yards which drew a smart stop from Willy Gueret.

Peters then fired over in the 19th minute as Ipswich threatened to make the breakthrough.

Further efforts from Clarke and Sylvain Legwinski then narrowly missed the target before Swansea began to create chances themselves as the half wore on.

Shortly after the half hour mark, Leon Britton produced a cross which Butler met with a mishit shot which failed to trouble Ipswich goalkeeper Lewis Price.

But the hosts threatened again seven minutes before the break when Gary Roberts crossed for Lee, who headed wastefully over the crossbar.

Legwinski then tested Swansea goalkeeper Willy Gueret two minutes after the break with a drilled effort but Swansea came even closer moments later when winger Andy Robinson was denied by an excellent close-range parry from Price.

The visitors threatened again soon after when Adebayo Akinfenwa hit a shot which required a fine block from Fabian Wilnis.

Remarkably, Swansea threatened once again when Trinidad and Tobago defender Dennis Lawrence hit a 30-yard screamer which almost broke the deadlock.

In the 64th minute, a goal was scored, but it came from Ipswich as Lee fired home his 12th goal of the season from the spot after Tom Williams fouled Peters.

Swansea boss Jackett threw on Lee Trundle and Pawel Abbott and the move looked to have paid dividends.

Trundle made an immediate impact and saw a header saved by Price before hitting a shot which flashed narrowly wide.

And in the last minute, Ipswich were left breathing a sigh of relief after Abbott connected with Marcos Painter's cross, but Price produced another fine save to send his side into the last 16.

Teams:

Ipswich Price, Sito, Naylor (Casement 61), Wilnis, Harding,Peters, Legwinski, Williams (Haynes 85), Roberts, Lee,Clarke (Garvan 69).

Subs Not Used: Supple, O'Callaghan.

Booked: Lee, Sito.

Goals: Lee 64 pen.

Swansea Gueret, Duffy, Iriekpen, Lawrence,Williams (Painter 85), Britton, Tate, Pratley (Trundle 66),Robinson, Butler, Akinfenwa (Abbott 78).

Subs Not Used: Oakes, Jones.

Booked: Pratley, Robinson, Gueret, Williams, Tate, Britton,

Duffy.

Att: 16,635

Ref: N Miller (Co Durham).