Man United booked a place in the Carling Cup final but were pushed all the way by Derby, who lost 4-3 on aggregate.

Nigel Clough's Rams took a 1-0 lead from the first leg into Tuesday night's semi-final, but were 3-1 down on aggregate after just 34 minutes at the Theatre of Dreams following goals from Nani, John O'Shea and Carlos Tevez.

The visitors refused to give up their Wembley dream, though, and delivered an outstanding second-half display, which saw a period of domination rewarded with a Giles Barnes penalty 10 minutes from time.

That set up a grandstand finish which saw Barnes steer a good headed chance straight at the grateful Ben Foster on 84 minutes.

But the Red Devils played keep-ball for the closing stages, and won a penalty of their own on 87 after Roy Carroll fouled Tevez, with sub Cristiano Ronaldo keeping his cool to convert the spot-kick to make it 4-1 on the night.

Barnes, who had replaced Kris Commons on 69, curled in a delicious 20-yard free-kick in stoppage time - but it was too little, too late.

The game started well for Derby, with first-leg hero Commons whistling a fierce 25-yard strike narrowly wide of the upright.

It was United who opened the scoring, though, when Nani thumped an unstoppable 25-yard angled drive past the diving Carroll on 16 minutes.

It was 2-0 six minutes later when Tevez and Danny Welbeck combined superbly to set up O'Shea, who had far too much time to sidefoot home.

Welbeck was denied by a fine Carroll save, but the Rams keeper was beaten again on 34, when Rafael's right-wing cross was headed home by a completely-unmarked Tevez.

After the break, the Rams emerged rejuvenated by a half-time blast from Clough and took the game to Sir Alex Ferguson's men, with Commons, Rob Hulse and Paul Green all spurning good chances.

The introduction of fit-again midfielder Barnes brought the tie to life, but he could not prevent United from booking another trip to Wembley, where they will face either Burnley or Tottenham, who play on Wednesday night.