And despite seeing Rooney score all four goals in the 4-0 weekend win against Hull, Manchester United manager Ferguson claimed his performance against City scaled even greater heights.
Related ArticlesMan Utd 3 Man City 1; agg 4-3Tevez relishes role as fall guyMan City making their voice heardUnited restore orderUnited face action after Bellamy hitFerguson backs Ferdinand appealFerguson said: 'I thought Wayne was much better than he was on Saturday and he scored four goals against Hull.
'His control, his leading of the line and his penetration were absolutely fantastic tonight. It was a wonderful performance and a true world-class display.'
United, trailing 2-1 from the first-leg, appeared set for extra-time when Carlos Tevez's 76th-minute goal cancelled out earlier strikes by Paul Scholes and Michael Carrick.
But Rooney's header settled the tie and booked Ferguson's seventh League Cup final as a manager.
Ferguson said: 'It was a derby game and you like to win your derby games, but the fact it was a semi-final added a lot of spice to the match and scoring so late brought a special type of celebration.'
With last week's first-leg overshadowed by the public feud between Tevez and United captain Gary Neville, plus trouble among supporters off the pitch, both the Football Association and Greater Manchester Police had called for restraint in the second-leg.
The Bellamy incident will be reviewed by the FA today (Thurs) and United are likely to face punishment with City's Javier Garrido also being struck by a coin during the Premier League clash between the two clubs at Old Trafford last September.
On the pitch, referee Howard Webb firmly controlled the two sets of players, but United midfielder Darren Fletcher admitted it was key that the home side allowed actions to speak louder than words.
He said: 'There is great rivalry between the two clubs and we know about everything that went on in the first-leg.
'But it was important for us to go onto the pitch and let our football do the talking.
'It's easy to talk and whatnot, but you have to do it on the pitch and that's what we did tonight.'
City manager Roberto Mancini insisted his team can still emerge with silverware this season, despite bemoaning the defensive frailties that contributed to their defeat.
He said: 'Next time, we must pay more attention. If you leave one chance to Rooney, he scores. United have the players to score.
"We had a big chance to get to the final but now we have to concentrate on the FA Cup and the Premier League.
'I am very sorry for the players and fans because we played well. We just had ten minutes when we did not and we conceded two goals.'