On-loan Liverpool starlet Wilson had missed the past two matches for his temporary club with a hip problem, with Derby losing and drawing in his absence.
The attacking midfielder was drafted straight back in for the third round replay by boss Frank Lampard—such has been his impact on the side and goalscoring threat this season.
Then Wilson took over.
The Welsh wizard has gained a reputation for hitting some stunning free-kick goals this term for club and country, and he proved his set-piece prowess once again to pull one back on 76 minutes.
A dangerous ball was whipped in from the right side of the box, more designed as a cross than direct shot, but the placement and pace on the ball was the perfect type of dual-threat free-kick: dangerous cross, but also on target.
It evaded every Saints defender and the goalkeeper, and nestled in the far corner of the net to give Derby hope.
With the clock ticking down inside the last 10 minutes, Wilson then turned provider, swinging over another brilliant cross which was headed home by team-mate Martyn Waghorn from close range.
The key switch for Wilson to take control of the game came in a second-half tactical alteration, which saw him head back out to the right flank, from where he has often proven so deadly.
Wilson’s impact forced the game into extra time—but his race was run just a few minutes later, with Lampard opting to sub his talented 21-year-old soon after the restart.
There were no further goals in extra time and Derby eventually prevailed, 5-3 on penalties.
The Welshman now has 11 goals and three assists to his name during his loan spell with Derby.
Harry Wilson (21) has completely changed this FA Cup tie since moving out to the right.
A well-taken free-kick finds the back of the net to get Derby County back into the game, before whipping a fantastic cross onto the head of Martyn Waghorn for the equaliser.
— Scouted Football (@ScoutedFtbl) January 16, 2019
8 – Harry Wilson has scored eight goals from outside the box for Derby County in all competitions this season, at least twice as many as any other player in the top four tiers of English football in 2018-19. Specialist. #FACup #SOUDER pic.twitter.com/DcLtuWBdGg
— OptaJoe (@OptaJoe) January 16, 2019
Harry Wilson has got to be in the Liverpool first-team squad next season.
He could be a potential game-changer with his ability from long-range and free-kicks
— ReviewFootball (@ReviewFootball) January 16, 2019
— Derby County (@dcfcofficial) January 16, 2019