Ian Holloway's Seasiders, promoted from League One via the play-offs in 2007, went behind to Chris Cohen's thunderbolt in the 13th minute but Keith Southern levelled midway through the first half before Charlie Adam slotted home a penalty just before the hour mark.
Forest have an impressive home record this season and will still fancy their chances of turning the tie around but Billy Davies' side have now not won on their travels now since a 3-1 win at West Brom back in January lifted them into an automatic promotion spot.
Matt Gilks denied them a late equaliser when he turned away Robert Earnshaw's low drive in the dying moments but Blackpool probably just about deserved their advantage from an enthralling end-to-end game.
They were unchanged from the side that started against Bristol City last week, while Forest made a total of eight changes following their draw at Scunthorpe.
Goalkeeper Lee Camp, Wes Morgan, Cohen, Chris Gunter, Paul McKenna, Dexter Blackstock, Radoslaw Majewski and Nathan Tyson were all recalled by Davies.
Tyson crashed a 20-yard shot over the crossbar in the fourth minute and while Blackpool forced a couple of early corners, it was Forest who seized the advantage in the 13th minute.
Blackpool only half-cleared a free-kick into their penalty area and when the ball broke to Cohen on the left edge of the box, the former West Ham lashed a rising shot beyond Gilks and into the far corner.
But Blackpool hit back with a well-worked equaliser in the 26th minute.
Seamus Coleman weaved his way across the area and found Ian Evatt, who played the ball back across the six-yard line for Southern to convert.
Blackstock's header came back off the crossbar moments later at the other end and Tyson's follow-up rolled agonisingly wide as both sides threatened when ever they broke forward.
Coleman then cleared Morgan's goalbound shot off the line in first half stoppage time.
Tempers flared eight minutes after the restart, with Blackstock and Coleman both booked for some argy-bargy after a contested throw-in.
Blackpool took the lead in the 57th minute. DJ Campbell's brilliant run carried him into the area and after playing a one-two with Brett Ormerod the little striker was tripped by Forest defender James Perch.
Staffordshire referee Phil Dowd pointed straight to the spot and Adam stepped forward to coolly place a left-footed penalty into the bottom corner.
Blackstock headed Tyson's superb cross inches wide midway through the second period, while Campbell spurned a gilt-edged chance for the Seasiders after being played in by Adam.
Forest goalkeeper Lee Camp did well to smother Ormerod's point-blank shot and Blackpool substitute Stephen Dobbie fired a left-footed shot wide as the Tangerines looked to add a third goal that would have given them more leeway going into the second leg.