Substitute Lee Barnard rescued a late point for Saints at the Withdean as four goals were shared with Brighton.
Elliott Bennett put Brighton ahead inside the opening quarter of an hour with a fine left foot finish from a clearance which gave Kelvin Davis no chance of stopping.
The Seagulls had further chances early on and were punished for not taking them when former Albion player Dean Hammond netted a late first half equaliser with a glancing header from Jason Puncheon's whipped free-kick.
In the second half the goal scoring pattern repeated itself as Gus Poyet's side got back in front as substitutes Kazenga Lua-Lua and Ashley Barnes linked up for a brilliantly taken headed goal from 12 yards out.
But Saints had a replacement of their own to thank for a crucial second leveller which arrived in the 89th minute to keep the play-off ambition alive as Barnard crashed home from close range to take a point back for the relatively short journey home.
Brighton: Brezovan, Elphick, El-Abd, Navarro (Arismendi 78), Crofts, Carole (Lua-Lua 57), Bennett, Painter, Calderon, Murray (Barnes 62), Dicker. Subs (not used): Walker, Virgo, Holroyd, Hendrie.
Saints: Davis, Otsemobor, Jaidi (Barnard 75), Fonte, Harding, Antonio (Seaborne 75), Wotton (Papa Waigo 75), Hammond, Puncheon, Lallana, Lambert. Subs (not used): Bialkowski, Perry, Mills, James.
Referee: Mr. S. Tanner (Avon)
Attendance: 7,784 (including 885 away)
Both Jason Puncheon and Jon Otsemobor returned to the starting line up after missing out through injury and being cup-tied in recent matches.
Saints got things underway defending the away 'end' with the stand holding the travelling support separated by the thick end of the running track at the Withdean stadium.
A lively start to the game saw early sights of goal for both sides in the opening five minutes of play, Saints going closest first when Lambert's low cross shot Antonio was narrowly missed by Michail Antonio diving in at the far post.
Elliott Bennett got some space on the Seagulls' right and drilled in a dangerous centre for the hosts' first effort, which Glenn Murray blazed over when well placed in the area.
Another spurned opportunity from Murray this time from close range looked to have ended Gus Poyet's men's early endeavour, but Albion eventually found the back of the net in style on 12 minutes after a foul which saw former Seagulls midfielder Dean Hammond booked.
The resulting free-kick was cleared invitingly into the path of Elliott Bennett, who smashed home a rasping shot from the edge of the box to give Brighton an early lead.
Saints nearly hit back just six minutes later when Lambert's long range free-kick in the 18th minute brushed the top of the bar on its way towards Peter Brezovan's goal.
Shortly afterwards Paul Wotton turned up the pressure from the visitors by going agonizingly close with a ferocious strike on the end of Lallana's corner which just whistled past the post
The high tempo nature remained as the match reached the half hour mark and ten minutes before the break Lambert was denied as he connected to Puncheon's corner from the right.
Lambert was then fouled just outside of the area, but Puncheon's central free-kick didn't clear the wall. His next effort from the left five minutes before the break fared much better as Saints drew an equaliser from a former Albion player.
Puncheon's curling delivery from the right was glanced into the bottom corner from the head of Dean Hammond to level the scores on 40 minutes.
An entertaining first half saw one additional minute for stoppages during which time Lallana was denied a shot on target from a last ditch challenge by defender Adam El-Abd.
Half Time: Brighton 1-1 Saints
The second 45 began in the same manner as the previous half had ended, and Saints went close to repeating their equalizing goal when Puncheon delivered another dangerous ball in, but Brezovan collected the deflected effort as it dropped from the air.
At the other end, Murray was cautioned for diving as he tried to fool referee Steve Tanner by going down inside the area.
On 55 Puncheon waltzed his way through the middle and eventually fired a crisp shot wide as Saints went desperately close to taking the lead, prompting a first change of the game for the hosts as Kazenga Lua-Lua replaced Sebastien Carole in attack.
Puncheon's determination saw him recover a lost cause before striking a firm effort at Brezovan which the 'keeper knew little about.
Albion then brought Ashley Barnes on for Murray and swift counter-attacks from either side ended with Lua-Lua hitting the side-netting from the left, but then tellingly on 66 minutes the two substitutions combined to restore the hosts' lead.
Lua-Lua swung a terrific ball into the box and Barnes, less than three minutes after entering the field of play planted a firm header off the base of the far post to make it 2-1.
Inigo Calderon let fly from distance as the hosts continued to threaten, leading to a triple substitution from Alan Pardew. Jaidi, Antonio and Wotton were all withdrawn as Daniel Seaborne, Papa Waigo and Lee Barnard tried to salvage the match for Saints.
Barnard saw yellow for going to ground too easily before Albion made their final switch with Alan Navarro replaced by Diego Arismendi.
On 81 Barnard was hauled down around 30 yards from goal, but Lambert was inaccurate with his strike on this occasion.
Brighton invited pressure on to themselves as Saints pushed all ten outfield players into the Albion half which resulted in Hammond going close to his second, but Brezovan was equal to his shot from the edge of the box.
But the pressure told as late drama ensued when the visitors pulled level again in the last minute of the ninety.
Subs Waigo and Barnard linked as the former picked out the former Southend striker with a drilled cross that Barnard dispatched from inside the six yard box to make it 2-2.
Four minutes were added on as Saints threw everything forward. Hammond saw another shot saved by Brezovan, and Fonte was pushed forward into attack, but time ran out as a stalemate was the final outcome in East Sussex.
Full Time: Brighton 2-2 Saints
