The game was only five minutes old when the floodlights fused, but after a 40-minute delay proceedings resumed and the near 23,000 crowd witnessed an exciting to-and-fro affair.
Ipswich twice went ahead through Richard Naylor and Owen Garvan's first senior goal, but Saints always looked dangerous going forward, particularly on set plays and twice levelled through Darren Powell and Dennis Wise.
The early action had been end-to-end, but once play resumed after the light incident it was nearly all Saints as they pegged Ipswich back in their own half for long spells.
A dangerous low Wise cross just eluded Matt Oakley, before Brett Ormerod pounced on a defensive mix-up between Naylor and Fabian Wilnis to fire in an angled shot which Lewis Price tipped around the post.
Dean Bowditch poked just over after Jason De Vos flicked on a long throw from Wilnis and then another Wilnis delivery was cleared only as far as Garvan, whose low effort was blocked.
Danny Higginbotham burst clear from defence onto a Kamil Kosowski pass, but blazed into the near post sidenetting when he probably should have gone across goal.
Antti Niemi showed his class with two fine low saves to deny Sam Parkin and Garvan, before Ipswich went ahead on 36 minutes, Naylor rising at the far post to head home a Darren Currie corner.
Town were on top now and De Vos nodded dangerously into the six-yard box, but it was scrambled clear before Parkin's firm header from a Wilnis cross cleared the bar.
Ricardo Fuller fired over straight after the restart, but Saints levelled on 49 minutes when Powell rose highest to nod home a Dennis Wise corner for his first Southampton goal.
Saints had the bulk of the pressure for the next ten minutes without creating too much, and Town made them pay on 61 minutes when a Currie corner was only cleared as far as Garvan on the edge of the box and he controlled before shooting left-footed beyond Niemi.
Tomasz Hajto saw a stinging 25-yard volley tipped over by Price, Matt Richards cleared another Powell header off the line and then the outstanding Nigel Quashie struck a fierce drive against the post with Claus Lundekvam unable to turn in the rebound.
An equaliser appeared on the cards and it duly arrived on 69 minutes when Higginbotham's raking crossfield ball found Oakley and he cleverly volleyed back across to the far post where Wise got his head on the ball to bundle it in.
Saints looked favourites to go on and win at the point, and Price almost fumbled a Quashie shot into his own goal, the effort just bobbling past the post, before a Wise shot on the turn went well wide.
Kosowski played in Ormerod whose angled drive was superbly turned away by Price - a former Southampton trainee - before Niemi got down well to direct a low Currie shot away from danger.
Price dropped on a loose ball on his goal line after a Quashie corner caused havoc and then Currie had a penalty shout waved away as he tried to beat Hajto just inside the box.
In added time, Town sub Dean McDonald volleyed wide from the edge of the box, then at the other end Saints had a late winner ruled out for offside when Wise's free-kick was bundled home but the flag was up long before.