Keegan's Premiership title dream disappeared into the Trent End net when Woan struck his late equaliser on Newcastle's visit to Nottingham in May. Yesterday, Kenny Dalglish was the manager left suffering on the Newcastle bench as Woan rediscovered his particular Forest fire with a vengeance.
Up to the final 15 minutes, the midfielder's measured prompting seemed the only thing likely to open up a tightened Newcastle defence. Ultimately, his shooting power did more than that.
Twice in three minutes the Merseysider let rip with his lethal left foot. And on both occasions he found the back of the Gallowgate End net.
Thus Newcastle's pragmatic passage into the FA Cup fifth round became a knockout blow instead. The Toon Army would not have appreciated the irony, but Woan had not scored since that fateful May night at the City Ground.
It was evident by the silence which accompanied much of yesterday's Sunday service at St James' that the locals did not appreciate the markedly different vision they beheld in their beloved black and whites.
The cavalier approach of the Keegan days was conspicuously absent from the home ranks. In its place was a roundheaded caution reminiscent of how so many defensive holes were covered up in Blackburn, Lancashire.
Instead of the attacking licence they enjoyed under Keegan, Peter Beardsley and Robert Lee were clearly under instructions to err on the side of defensive protection in their midfield duties.
It was such an emphatic departure for Newcastle that their attacking endeavour before the break amounted to two headers, one each by Alan Shearer and Les Ferdinand, both of which looped wide of Mark Crossley's goal.
There was even the novel sight of Newcastle's back four successfully indulging in a little defensive formation dancing, as they advanced together to play Bryan Roy offside.
The objective, of course, was to subdue the opposition and Forest were duly restricted to one half-chance in the first 67 minutes, Roy lobbing Shaka Hislop but missing the target after Woan's slide-rule pass found him unmarked on the left angle of the Newcastle box.
Openings, however, were at an unfamiliar premium for Newcastle. Crossley, apart from an early deflected David Ginola shot that would have been ruled out for an off-the-ball infringement, did not have a save to make until the 51st minute.
The Forest goalkeeper got his right hand to the header Ferdinand despatched from Warren Barton's cross from deep on the right nine minutes later but it was not enough to keep the ball out of his net.
Had Shearer beaten Crossley when he was put clear two minutes later, the outcome might have been different. As it was, with Newcastle threatening a clean sheet and 13 minutes remaining, Woan swung his left boot from a range of some 30 yards and his low shot was deflected by both Barton and Keith Gillespie on its way into the bottom right corner of Hislop's goal.
If his first goal was more than a touch fortunate (two, to be precise), Woan's second was in the clinical class. After Barton skied an attempted clearance, the Forest midfielder controlled the ball with his chest and struck it on the bounce over Hislop and into the net off the underside of the bar.
Only then did Dalglish throw caution to the Tyneside wind, withdrawing Barton and ushering black and white bodies up-field. Lee and Ferdinand both went close but the cause was already a lost one for Newcastle.
"How do I explain it?" Dalglish retorted in the press room. "It's a bad question to start with.
"I thought we did more than enough. You can't legislate for two ricochets and a wonder goal.
"Defensively, apart from those two instances, we had not too many problems. Every successful team has a slice of luck and we aren't getting any at the moment."
Forest had theirs yesterday but they earned it. Unlike Dalglish, their manager was in a position to lead from the front line and the clenched fist raised by Stuart Pearce to his colleagues after Ferdinand's goal was the signal for Forest's fightback.
They have now won six of their eight games under the England left-back's player-management, five in a row, and Woan attributed their mid-season revival to Pearce's fighting qualities. "It's the Psycho attitude he's brought into the dressing room," Forest's goalscoring hero said.
And the Psycho analysis? "It's just a little bit of confidence," Pearce said. "The lads are gaining it by the week."
Goals: Ferdinand (60) 1-0; Woan (77) 1-1; Woan (80) 1-2.
Newcastle United (4-4-2): Hislop; Barton, Elliott, Peacock, Beresford (Watson, 19); R Lee, Beardsley, Batty, Ginola (Gillespie, 63); Shearer, Ferdinand. Substitute not used: Clark.
Nottingham Forest (4-4-2): Crossley; Lyttle, Chettle, Cooper, Pearce; Phillips, Haland, Bart-Williams, Woan; Roy (J Lee, 82), Campbell. Substitutes not used: Gemmill, Fettis (gk).
Referee: G Ashby (Worcester).
Bookings: Forest: Cooper, Haland.
Man of the match: Woan.