Preston held firm to book their place in the Championship play-off final against West Ham on 30 May after they secured a goalless draw at Derby.
Preston defended a two-goal lead from the first leg and Derby's only real chance was a late penalty, Grzegorz Rasiak striking against the post.
Long-range efforts from Tom Huddlestone and Rasiak failed to trouble Carlo Nash as Derby looked short of ideas.
Marco Reich prodded over from close range and Nash saved well from Rasiak.
Derby boss George Burley provided a huge shock with his team selection, finding starting slots for Rasiak and Inigo Idiakez, who had both been expected to miss out with injuries.
There was a ferocious tempo at the start and it was Preston who enjoyed the better of the early stages as they sought a killer third goal in the tie.
Derby, backed by a vociferous capacity crowd, soon got into their stride with the lively Paul Pechisolido proving a menace up front.
But Preston were doing their best to stifle the life out of the game and deny their hosts any room in which they could play, with former Ram Youl Maweye a huge presence at the back.
Indeed in a chanceless first half Derby were restricted to just three long-range efforts, Huddlestone twice and Rasiak both failing to trouble Nash.
The Pride Park faithful seemed nervous as the second half began and they were lucky their side were not almost immediately down to 10 men - Rasiak's ill-advised lunge on Maweye only bringing him a warning as he had already been booked.
Burley brought on club captain Ian Taylor on the hour mark and he provided them with some impetus as the Rams were unfortunate not to win a penalty.
A Bisgaard corner was heading for substitute Reich and he prodded over from six yards as it looked like he was being held by Brian O'Neil.
The Rams were given a lifeline by referee Richard Beeby with eight minutes to go when he gave them a soft spot-kick for Chris Lucketti's challenge on Rasiak.
But the Polish striker could only send his left-foot shot against Nash's right-hand post and with it went Derby's chances of playing in the Premiership next season.
Derby: Camp, Jackson, Konjic, Huddlestone, Kenna (Taylor 61), Bisgaard, Idiakez, Bolder, Smith (Reich 45), Rasiak, Peschisolido.
Subs Not Used: Miller, Mills, Junior.
Booked: Rasiak, Peschisolido, Idiakez.
Preston: Nash, Hill, Davis, Lucketti, Mawene, Lewis (Broomes 90), McKenna, O'Neil (Etuhu 84), Sedgwick, Nugent (Agyemang 86), Cresswell.
Subs Not Used: Ward, Mears.
Ref: R Beeby (Northamptonshire).