As a player, O'Neill won the competition twice with Nottingham Forest and repeated that feat at Leicester City. After this win over Portsmouth he is on the brink of what would be a seventh career appearance in the final.
Related ArticlesGrant wants to splash cash in JanuaryAvram Grant faces a new challenge at Fratton ParkAvram Grant: Portsmouth can avoid dropPremier League set for record transfer windowSport on televisionJudging by the way he selected a virtual full-strength team and danced down the touchline to celebrate the decisive goal, there is no question he is serious. Villa's scorers will have also provided encouragement to Fabio Capello, with Emile Heskey, James Milner, Stewart Downing and Ashley Young all contributing.
For Aston Villa, there was the pleasing sight of a first start for Stewart Downing after he had arrived from Middlesbrough for £12 million during the summer while nursing a broken foot. Downing was used to the left of a midfield four as Milner, who has started on the right this season, was switched to a central position alongside Stilyan Petrov.
Milner adapted quickly and was a pivotal figure as the match exploded into life with three goals inside 27 minutes.
Portsmouth actually took the lead when Danny Webber's corner was sliced into his own goal by Petrov, but the response from Villa was emphatic. Richard Dunne played the ball into the path of Milner, whose cute pass was converted by Heskey with a chip over Portsmouth goalkeeper Asmir Begovic.
Having provided an assist, Milner then produced an outstanding finish after collecting Ashley Young's throw and turning to curl a shot beyond Begovic.
The spirit that has been so admirable at Portsmouth even in this chaotic season was, however, still evident as Nadir Belhadj, Hassan Yebda and Webber all almost conjured a first-half equaliser.
Yet with Avram Grant fielding a weakened team, there was a lack of cutting edge and confidence in the final third despite plenty of second-half possession.
By contrast, Villa were incisive on the counter-attack and clinched their place in the semi-final when Downing headed Ashley Young's cross past Begovic. Kanu briefly gave Portsmouth hope but Young quickly condemned Grant to a second straight defeat with Villa's fourth.
Portsmouth (4-4-2) Begovic; Vanden Borre, Ben Haim, Kaboul, Hreidarsson; Yebda, Hughes (Wilson 84), Brown, Belhadj; Webber (Kanu 65), Utaka (Piquionne 65). Subs: Ashdown, Mullins, Dindane, Basinas. Booked: Brown, Vanden Borre, Kaboul.
Aston Villa (4-4-2) Guzan; L Young, Dunne, Cuéllar, Warnock; A Young, Milner, Petrov, Downing; Abonlahor, Heskey (Delfouneso 89). Subs: Friedel, Delph, Reo-Coker, Beye, Gardner, Clark.
Referee: L Mason (Lancashire).