Ipswich made it 12 home wins on the spin and moved up to fourth by brushing aside Southampton with Jon Walters and Pablo Counago netting in either half.
Walters opened the scoring 11 minutes before half-time when he deflected a shot past Saints keeper Kelvin Davis.
Southampton did put pressure on with Ipswich keeper Neil Alexander saving from Bradley Wright-Phillips and Stevie Hammell hitting the post from 20 yards.
But Counago made the points safe with a thumping header in the 69th minute.
Ipswich manager Jim Magilton: "We were lucky with the first goal and were a little bit nervy. It was a scrappy win but I am delighted with a clean sheet and three points.
"We had to dig in and we did. In the end we showed that little bit more quality which made the difference.
"There were times when we were a little bit low but the crowd lifted us and the players appreciated it."
Ipswich: Alexander, Wright, Bruce, De Vos, Harding, Walters, Miller (Legwinski 90), Garvan (Williams 67), Clarke (Haynes 85), Counago, Lee. Subs Not Used: Supple, Wilnis.
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