Derby County have one foot firmly in the Championship play-off final at Wembley on 24 May after completing a hat-trick of victories this season over Brighton & Hove Albion.
They beat the Seagulls home and away on their way to third place in the table and will be confident of completing the job at the iPro Stadium on Sunday evening.
Steve McClaren's side overcame the shock of conceding an early goal to dominate the opening half of this play-off semi-final first leg with their pace and control on the break.
Chris Martin levelled with his 21st goal of the season – his third against Brighton – from the penalty spot, and it was Martin's shot that deflected in off the unlucky Brighton goalkeeper Tomasz Kuszczak to give Derby the lead.
When Brighton tried to strike back in the second half, Derby goalkeeper Lee Grant kept out everything they could throw at him.
It was Brighton's first defeat in nine games and they will need to produce the sort of performance on Sunday that brought them nine league wins on the road this season, including three-point hauls at champions Leicester and one of the other play-off semi-finalists Wigan.
They had looked dangerous early on whenever Will Buckley was in possession and he opened the way for Brighton to take the lead after 18 minutes when his flick allowed right-back Inigo Calderon to set up Jesse Lingard. The Manchester United loanee's first shot was blocked but he thrashed his second past Grant from 10 yards.
But Derby were level after 28 minutes when one of a number of quick breaks ended with left-back Craig Forsyth charging into the heart of the Brighton defence. Matthew Upson's challenge was nowhere near the ball and Martin, who scored twice in Derby's 2-1 win at the Amex in August, converted the penalty.
This should have been a warning to Brighton that Derby's pace was going to be a danger on the counter-attack, but it seemed to go unheeded. Johnny Russell and Craig Bryson both went close after pouncing on misplaced passes by Brighton players and speeding clear of defenders.
The momentum was now firmly with Derby and it came as no surprise when they took the lead in first-half injury time, although there was an element of fortune about the goal.
A quickfire burst of passing had Brighton chasing shadows, and Martin was unchallenged as he unleashed a fierce rising shot that beat Kuszczak and crashed against the crossbar. However, when the ball came back into play it hit the prone goalkeeper on the back and rebounded into the net.
Brighton needed to regain the initiative, and they introduced winger Kazenga LuaLua at the interval in an attempt to force Derby back, but Calderon put a decent chance into row Z and Leo Ulloa's bouncing, goal-bound shot was fingertipped on to the crossbar and to safety by Grant.
The Derby goalkeeper bettered that 10 minutes from time to touch over Stephen Ward's 20-yarder for a corner seconds after he had pushed aside a long-range effort by Lingard. Brighton need to do better than that on Sunday.
Uwe Rösler refuses to play mind games with QPR
Wigan manager Uwe Rösler is not prepared to engage in "pressure bingo" before his team's meeting with Queen's Park Rangers, as two of last season's relegated sides bid to return to the Premier League.
The Derby manager, Steve McClaren, stressed it was a "must" for two clubs playing in the top flight last year to achieve promotion.
But Rösler, before Friday night's semi-final first leg, said: "What we have now is pressure bingo. I'm not going in that direction. But when [QPR boss] Harry Redknapp says we are the clear favourites for promotion, then I have to smile a little bit.
"Harry said we have the best squad – I think we have a very good squad – but Harry has probably a three times bigger wage budget than we have."
Second leg dates
Sunday Derby v Brighton (5.15)
Monday QPR v Wigan (7.45)
Final Sat 24 May (Wembley)