Lee Williamson was on target for the second time in three days against Swansea to earn Watford a place in the Carling Cup quarter-finals with a 1-0 win.

The midfielder, who broke his duck for the season in Sunday's Coca-Cola Championship defeat at the Liberty Stadium, made no mistake with a 21st-minute effort to exact some revenge in tonight's quick-fire rematch.

It was no more than the visitors deserved as the hosts failed to provide any real punch.

Hornets caretaker boss Malky Mackay took his side back to south Wales on the back of a 3-1 reverse but looking to do his prospects of landing the job on a permanent basis some good.

Despite having a place in the last eight at stake, City boss Roberto Martinez made eight changes to his starting line-up, including a debut for on-loan Aston Villa defender Stephen O'Halloran.

Mackay responded with five of his own, the cup-tied Darren Ward a notable absentee.

The first real chance of the game fell to the hosts. Guillem Bauza showed good awareness to drop the ball in behind the Watford back four for Febian Brandy to race onto, the former Manchester United youngster outstripping the back line before firing narrowly wide of goalkeeper Richard Lee's far post.

Tamas Priskin headed wide after 15 minutes as the Hornets pressed, and Jobi McAnuff called Swans goalkeeper Dimitrios Konstantopoulos into action soon after.

The pressure finally paid off when Priskin linked up well with Tommy Smith in attack and Williamson burst through from midfield to finish from 12 yards out with a right-foot finish.

The Swans struggled to find their feet as the half wore on, Bauza's cross causing some trouble as Lee fumbled to the ever-alert Brandy, but he was unable to pick the ball out of his feet to convert.

Priskin fired wide again before the whistle but the advantage remained the same at the break.

The hosts continued to toil and after 12 minutes of the second half Martinez had seen enough, making a double substitution from the seven at his disposal, bringing Jordi Gomez and Mark Gower on for Owain Tudur-Jones and Bauza respectively.

Brandy continued to knock on the door, finding space enough to get his shot off from the edge of the box but Lee was equal to it.

Mackay brought on Grzegorz Rasiak in place of Priskin, who had worked tirelessly throughout, to freshen up his forward line as his side moved within 14 minutes of progression, Will Hoskins coming on for McAnuff.

Martinez took his last throw of the dice by taking off Brandy and bringing on Sunday goalscorer Jason Scotland with five minutes remaining.

His salvation almost arrived from the boot of Gomez, who saw his free-kick come back off the inside of a post but roll safe, much to the agony of the home faithful.

But any hopes of a late leveller faded away to leave Mackay with a potential date with one of the big boys as his side's Wembley dream lives on.