Birmingham City won a dramatic penalty shoot-out to reach the quarter-finals of the Carling Cup on a night of high drama at the New Den.

Steve Bruce's side twice threw away a lead and had to rely on Stan Lazaridis' winning penalty for a place in the final eight. Julian Gray and Emile Heskey were on target but they were pegged back by Alan Dunne and Marvin Elliott's 116th-minute piledriver.

While Bruce will be delighted to be in the hat, he will have been alarmed at his side's fragility. He will also be woried by the fact that Heskey suffered a twisted knee and is a major doubt for the Premiership game against West Ham United on Monday night.

Two of Birmingham's longest- serving players proved to be Bruce's matchwinners. Nico Vaesen produced another penalty save in the shoot- out and Lazaridis kept his cool to ensure Birmingham avoided an embarrassing defeat.

It all started so differently, with Gray particularly prominent. He fired high and wide from a Jermaine Pennant cross after six minutes but adjusted his radar to hand Birmingham the lead with their next opportunity.

It followed a slick passing move that was a sign of their growing confidence. Mario Melchiot exchanged passes with Pennant before feeding Heskey and his crafty pass freed Gray 12 yards from goal.

However, there was still plenty of work to do for the winger as he was at an acute angle, but he struck a sweet drive past Lenny Pidgeley that flew into the top corner of the net.

Birmingham created opportunities at will with Gray in particular terrorising Paul Ifill. Matthew Upson was left unmarked on four occasions from Pennant corners and he forced Pidgeley into action on three occasions.

But it wasn't only set-pieces that were causing Millwall consternation, as Gray raced to the byline for the umpteenth time and pulled the ball back to Heskey 18 yards from goal, but the striker's lack of confidence showed as he snatched at the chance and skied his shot well over the bar.

Birmingham were in cruise control but, as so often this season, they were unable to keep their foot on the gas and allowed a poor Millwall team to grind their way back into contention.

Walter Pandiani's shot was deflected wide eight minutes after the break and the Uruguayan's next contribution was to prove costly. A quick throw-in by Jody Morris reached him in relative comfort but he dallied on the ball and was dispossessed by Dunne.

The temporary full-back cut inside and from 20 yards out unleashed a fierce curling shot that sailed over Nico Vaesen and nestled in the back of the net via the crossbar.

Heskey sliced wide from a David Dunn through-ball and when he intercepted a Carlos Fangueiro backpass and rolled the ball across the six-yard line, it looked as though it would be another frustrating evening.

Ben May's toe-poke flew inches wide and Elliott left Bruce with his heart in his mouth. Birmingham weathered the storm, though, striking gold from their ninth corner. Upson won yet another header and Pidgeley blocked his effort once again but as he spilled the ball slightly, Heskey pounced. However, Birmingham still failed to close out the tie and Elliott equalised four minutes from the end of extra time.

A long ball fell at the feet of the unmarked midfielder and he cracked a left-foot drive past the helpless Vaesen from the edge of the area to leave Bruce apoplectic with rage on the touchline. However, he was all smiles after the penalty shoot-out.