Peter Whittingham's equaliser five minutes from time capped a commanding second-half performance from Cardiff who kept their hopes of a Coca-Cola Championship play-off place alive.
Chris Baird struck with a 25-yard thunderbolt before Bradley Wright-Phillips grabbed a second to give Southampton a two-goal lead, after a first half in which Cardiff failed to impress.
Substitute Steven Thompson pulled one back for the visitors on the hour and set up a pulsating final third of the game, which came to life with Cardiff's second-half resurgence.
And Whittingham's superbly-hit late leveller forced a draw to dent Southampton's promotion hopes in the process.
Southampton asked the early questions and it was Rudi Skacel, fresh back in the first-team after a spell on the sidelines, who first brought Cardiff goalkeeper Neil Alexander into action with a drilled left-footed attempt from the edge of the box, which the Scotsman parried to safety.
Andrew Surman tested Alexander on the quarter-hour mark, left-footed from 30 yards, but his effort flew straight into the keeper's arms.
Cardiff's leading goalscorer Michael Chopra created the first real sign of danger from his side, lashing a long-range effort wide of Kelvin Davis' upright. And Joe Ledley had the Bluebirds' only other chance but blasted his 20-yard drive well wide of the right-hand post.
Baird gave Southampton the lead when he smashed home first-time after a Skacel lay-off from the right, sending his emphatic effort into the roof of Alexander's net on the half-hour mark.
And Saints left their mark on the first half when Wright-Phillips made it two, latching onto Marek Saganowski's header and slotting home from six yards just before the break, to give his side a flattering two-goal lead.
Despite a far from impressive first-half display, Cardiff came out for the second period with renewed optimism and quickly set about forging their way back in.
Chopra came close five minutes after the restart with a imaginative 30-yard free-kick but luckily for the hosts, Davis was well placed to make the save.
Cardiff boss Dave Jones made a change on the hour-mark, bringing off the largely anonymous forward Jason Byrne for Thompson and the substitute made an immediate impact.
Whittingham rolled an inviting ball across the six-yard box after a fast-paced Cardiff break, and Thompson was on hand to slot home into o a gaping empty net.
And Thompson almost turned provider for a Cardiff equaliser just five minutes later, this time playing in the lively Chopra, whose right-footed curler from the edge of the area was superbly tipped round the post by Davis.
The visitors were really beginning to press and five minutes from time Whittingham sealed a battling second 45 minutes with a deserved equaliser.
Chris Gunter's solid ball into the box was only half-cleared by Pedro Pele and and Whittingham let fly with a left-footed piledriver from 30 yards to grant the Welsh side a share of the spoils.
Teams:
Southampton Davis, Baird, Powell (Makin 46), Lundekvam, Bale,Surman, Pele, Viafara, Skacel (Dyer 65), Saganowski (Best 82),Wright-Phillips.
Subs Not Used: Bialkowski, Rasiak.
Booked: Viafara, Saganowski, Pele.
Goals: Baird 30, Wright-Phillips 44.
Cardiff Alexander, McNaughton, Johnson, Loovens (Gunter 66),Whittingham, Parry, Scimeca, McPhail, Ledley, Chopra,Byrne (Thompson 60).
Subs Not Used: Forde, Walton, Green.
Booked: McPhail.
Goals: Thompson 61, Whittingham 85.
Att: 20,383
Ref: I Williamson (Berkshire).