Will Packham made a nightmare mistake on his full debut as Albion bowed out of the FA Cup.
He gifted Jon Macken Preston's clinching second goal after Bobby Zamora had a penalty saved by David Lucas.
Packham received a late call-up when Michel Kuipers failed a fitness test on a back spasm.
The inexperienced keeper's big night went sour when Macken's 63rd minute shot from 25 yards slipped through his fingers.
Frenchman Eric Skora did just that on his away debut to give Preston a 16th minute lead.
Zamora, watched by several prospective purchasers had his spot kick saved at full stretch by Lucas three minutes later.
Packham, 21 last Sunday, was among three changes to the team which suffered a first League defeat under Taylor at Wigan on Saturday.
Brooker was preferred to Jones on the left and Webb partnered Zamora at the expense of Steele.
Preston named the side which came from behind to win 2-1 at Walsall on Saturday, with captain Sean Gregan still ruled out by a knee injury.
Everton manager Walter Smith and his assistant Archie Knox were in another sell-out crowd.
Smith watched Zamora score in spectacular fashion at Bury last month.
Also in the directors box were Taylor's predecessor Micky Adams, back at Withdean for the first time since his move to Leicester as Dave Bassett's No. 2, together with Charlton boss and former Albion midfielder Alan Curbishley.
They were joined by Crystal Palace chief Trevor Francis, Taylor's ex-skipper at Gillingham Andy Hessenthaler and special guest Mark Lawrenson, who played for both clubs.
Any butterflies felt by Packham must have eased by his first touch, a routine take from a massive kick by his counterpart Lucas which bounced once on its way through to Albion's rookie custodian.
Packham could do little when, having clawed away one corner, another by Preston captain Alexander was met beyond the far post by Murdock with a firm header which Mayo nodded off the line.
McKenna's follow-up from long range failed to hypnotise Packham as he gathered under the crossbar.
The visitors went ahead minutes later when Healy's diagonal cross found Skora at the far post. The Frenchman, substituted on his debut at Walsall, chested the ball down before calmly slotting past the advancing Packham from close range.
Albion were handed a great chance to restore parity within three minutes when Webb was pushed over inside the box by Murdock from a Watson corner.
Ref Rob Harris pointed straight to the spot but Zamora's penalty was pushed for a corner by Lucas diving full length to his right.
It was Zamora's second penalty miss this season, having failed to complete a hat-trick from the spot at Wrexham in September, but Lucas deserved credit for a fine stop.
The Seagulls, temporarily deflated, came close to conceding again on a number of occasions in the next few minutes.
Macken had a close range header saved at the second attempt by Packham.
The Preston striker, scoreless for 12 matches following a rejected £4. million bid from Wolves, then flashed an angled drive just wide of the target from 16 yards.
Albion were trying hard to respond and a dangerous low cross from Mayo just eluded a decisive touch from a team mate.
Webb glanced a header wide and a positive run by Brooker produced a corner as Albion continued to suggest they were by no means out of the tie.
The Seagulls were enjoying their fair share of possession, but there was an incisiveness about Preston when they attacked and Macken headed wide another chance to double their advantage.
Albion piled on the pressure approaching the interval with a succession of corners. The last of them from Watson was missed by penalty hero Lucas, but a colleague came to his rescue.
Albion could not afford to fall further behind,but they nearly did three minutes into the restart. Mayo presented possession to Macken, whose shot on the run was smothered away by Packham.
Cullip and Carpenter got in each other's way when the latter shaped to shoot, then Zamora volleyed high and wide from just inside the area.
Albion were forced into a substitution on 56 minutes, Jones replacing Oatway.
Steele was introduced upfront in place of Webb on 61 minutes, but a disastrous blunder by Packham doubled the deficit two minutes later.
He somehow allowed Macken's shot from long range straight at him at a comfortable height to slip through his grasp.
You had to feel sympathy for the young stand-in. His only previous first team experience was as a late substitute for Kuipers at Halifax last season, 48 hours after Albion had clinched the Third Division title.
The Seagulls suffered another ban blow on 66 minutes.
Morgan and Hart are each facing automatic one match suspensions following yellow cards at Wigan and Watson followed suit for a foul on Healy.
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