Billy Davies' unbeaten return as Nottingham Forest manager was preserved by an injury-time mistake from Brighton goalkeeper Casper Ankergren.
Forest were chasing a club record-equalling seventh straight win but it looked like Davies would taste defeat for the first time in eight games when Will Buckley put the visitors back in front with five minutes remaining.
However, Ankergren, excellent until this point, allowed Henri Lansbury's shot to squirm beneath his body and the npower Championship play-off rivals shared the points.
Brighton took the lead through Leonardo Ulloa's 57th-minute strike before substitute Lewis McGugan sparked the late drama with Forest's first equaliser in the 82nd minute.
Davies' side stay fifth in the table but Albion leapfrog Leicester and move up to sixth place.
Fit-again Sam Hutchinson made his first start for Forest since mid-September.
Hutchinson, on loan from Chelsea, replaced Gonzalo Jara Reyes at right-back as the Chilean did not return from international duty until yesterday.
The Reds were otherwise unchanged from the side that started at Hull two weeks ago, with playmaker Lansbury recovering from the calf and shin problems he sustained while away with the England Under-21 squad.
Illness forced Brighton boss Gus Poyet to make two changes.
Tomasz Kuszczak, who pulled out of the Poland squad with a back injury sustained during the 3-0 win over Crystal Palace 13 days ago, was replaced in goal by Ankergren while Andrew Crofts came in for Liam Bridcutt in midfield.
Forest started brightly and dominated the first half.
Lansbury played a neat one-two with Simon Cox on the edge of the box before forcing Ankergren into a parrying save after six minutes.
The Brighton goalkeeper, making his first league start of the season, got down well to deny the same player again shortly afterwards.
Darius Henderson kept Ankergren busy with a 15th-minute volley and a couple of efforts either side of the half-hour mark.
Radoslaw Majewski was then denied by the Dane when he looked certain to score from just six yards out.
Poyet could count himself fortunate to get all 11 players back in the dressing room for half-time after Kazenga LuaLua was shown just a yellow card for reacting angrily to a Hutchinson challenge and pushing the full-back to the ground.
LuaLua was withdrawn at the break, with Dean Hammond starting the second half.
Brighton were much better when play restarted with Ulloa cutting infield from the left and curling a shot narrowly wide.
Ulloa then saw a volley headed off the line by Danny Collins after Forest keeper Karl Darlow failed to hold Andrea Orlandi's free-kick.
But the Argentine would not be denied a third time and when the ball broke to him from the resulting corner he slotted in into the back of the net from 12 yards out.
Darlow kept the hosts in the game midway through the second half with a good save to keep out Matthew Upson's header.
Forest piled on the pressure in search of an equalising goal. Cox flicked a shot wide and another Henderson volley was repelled by Ankergren.
They made the breakthrough with eight minutes remaining when McGugan squeezed a shot past Ankergren from a tight angle.
However, the hosts were level for just three minutes. Ulloa controlled the ball on the penalty spot before laying it back to Buckley who placed a low shot past Darlow.
Billy Sharp missed a glorious chance to equalise when Ankergren blocked his close-range effort.
It looked like their chance had gone but a speculative 25-yard shot from Lansbury somehow found its way into the net.