Southampton's recorded their second successive 1-0 away win to secure their place in the fourth round of The FA Cup.
Shane Long scored the decisive goal after 19 minutes which keeps Southampton fighting on two fronts.
A tight affair
The goal came after James Ward-Prowse burst into the area after being fed by Dusan Tadic's flick.
The goal was perhaps harsh on Ipswich defender, Luke Chambers. After Ward-Prowse burst into the box, his superbly timed tackle prevented him going any further however the loose ball fell kindly to Shane Long and his instinctive finish gave Saints the lead.
Before that, Ipswich had a goal ruled out for offside. Kevin Bru's lofted the ball to Stephen Hunt, whose first time effort beat Fraser Forster but the flag denied Ipswich a dream start.
Southampton restricted Ipswich to very few clear cut chances. Former Saint David McGoldrick struck an effort high and wide while Darren Ambrose's header went straight into the palms of Forster.
The two sides have had parallel seasons. Southampton lost their manager and bar Morgan Schneiderlin, their five best players.
Fast forward six months and they're on the cusp of European football and a trip to Wembley could be on the cards.
Koeman's signings, excellent coaching and togetherness of his squad have been the ingredients of Southampton's surprise rise into the Premier League's top four.
Meanwhile Ipswich manager Mick McCarthy can say his side have had a similar season. Firstly nobody had them down as favourites for promotion or even a play off place for that matter.
McCarthy is working on a tight budget at Portman Road and his squad has cost a mere £10,000. Incredibly, they sit 3rd in the Championship, one point off top spot.
He too has a togetherness in his squad, who like Southampton, are strong defensively.
On reflection, the game showed why the two clubs have such good defensive records. Neither keeper was really tested at all, especially in a second half that saw Southampton see the game out.
If there was a person out there who could sum up the game perfectly it would be The Tractor Boys' boss. McCarthy told the BBC: "thought the game was a damp squib. We were OK until they scored and then they killed the game.
"They're a good Premier League side. Neither goalkeeper has been worked too much, but they got the goal and they killed the game."
It was a professional performance from Southampton who are now showing strong resilience. That is a quality of a side that finishes in the top four of the Premier League.
Southampton will now turn his attention to the third part of Southampton's three straight away trips. They will take the 12 hour round trip to managerless Newcastle on Saturday.
Koeman is likely to reinstate Graziano Pelle to the starting lineup, who was rested at Portman Road.
Future looking bright
A result a St James' will mean Saints will be in the top four after 22 games. The fixtures that follow that are not all that daunting. They have home games against Swansea City, West Ham United, Liverpool and Crystal Palace. They also face away trips to QPR and West Bromwich Albion in their next six games.
They have the potential to come through that unbeaten. A home tie against Crystal Palace is a fantastic opportunity to reach the last 16 of The FA Cup.
This is looking like it could the most memorable season in Southampton's history.