Back in May, it was Watson’s last-gasp header that sent Wigan into dreamland as they completed a memorable victory over Manchester City at Wembley to lift their first major silverware in 81 years.
Nine months on, the same player came to his side's rescue again to book their place in the quarter-finals of this year's competition – his stunning strike from a 30-yard free-kick proving to be the winner.
Chris McCann had put the visitors ahead after 17 minutes with a side-footed finish from inside the box following Jordi Gomez's delivery, before Fraizer Campbell levelled the tie 10 minutes later when he pounced on a loose ball in the Wigan box.
But five minutes before half-time, Watson proved to be the hero again as he sent a shot from a long-range free-kick into the bottom corner, giving Cardiff goalkeeper David Marshall no chance.
The one sour note for Watson came when he was replaced in the second half by Josh McEachran after suffering a suspected injury.
Ole Gunnar Solskjaer's Cardiff side were dumped out of competition with a whimper, as they now turn their attentions to Premier League survival.
James Perch had the first shot on goal for Uwe Rosler’s visiting side when he advanced to the edge of the Cardiff box from the right wing and flashed a shot just wide of Marshall's right-hand post.
Wilfried Zaha was involved for Cardiff after 12 minutes when he cut past Watson in midfield and dummied with two step-overs but his shot was blocked.
The cup holders went ahead after 17 minutes when McCann broke free just outside the six-yard box to get on the end of Gomez’s cross from the left-hand side, converting to give Wigan the advantage.
The lead lasted just 10 minutes though - great play from Zaha again on the right leading to a goalmouth scramble before the ball finally broke free to Campbell, who dispatched clinically into the bottom corner.
Half-an-hour into the game, Zaha burst into the Wigan box again after another set of step-overs but his attempted cross was blocked.
Cardiff continued to threaten from the right as Zaha - at the centre of everything for the hosts - picked out Campbell in the box but he was unable to double his tally.
But five minutes from half-time Watson put Wigan in front again with the decisive moment of the match.
His thumping strike into the bottom corner gave Marshall no chance as he lashed home when a 30-yard free-kick was touched to him.
Cardiff started brightly immediately after the break, when Mats Daehli cut in from the left and sent a shot just wide of Ali Al-Habsi's post.
Wigan goalscorer Watson was replaced by McEachran, on loan from Chelsea, after 56 minutes - but his job had already been done.
Cardiff continued to push for an equaliser but Zaha and Daehli were unable to get the crucial breakthrough.
The latter flashed a shot over, via a touch from a defender, with time running out but Cardiff did not have enough to force a replay.
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