The Swans survived an amazing Watford comeback to record their first away win in the Championship of the season.
Brendan Rodgers returned to Vicarage Road for the first time since leaving the club last year and saw his team storm into a 3-0 lead courtesy of Scott Sinclair, Stephen Dobbie and substitute Frank Nouble.
But with the victory looking secure,the Swans nearly committed soccer suicide as Troy Deeney and Martin Taylor sparked a remarkable Watford fightback with two late goals.
Then Martin Taylor headed home what looked like the equaliser in injury time only for the linesman's offside flag to come to Swansea's rescue.
It was Swansea's first away win in the league since March 9. Ironically, that victory also came at Vicarage Road.
The 3-2 success pushes the Swans up to eighth in the Championship.
Watford: Scott Loach, Andrew Taylor, John Eustace (C), Martin Taylor, Adrian Mariappa, Don Cowie, Danny Graham, Will Buckley (Troy Deeney, 67'), Lloyd Doyley, Jordan Mutch, Marvin Sordell. Subs: Rene Gilmartin (GK), Lee Hodson, Josh Walker, Stephen McGinn, Michael Bryan, Eddie Oshodi.
Swans: Dorus de Vries; Alan Tate, Garry Monk (C), Albert Serran, Neil Taylor (Angel Rangel, 63'); Ashley Williams, Mark Gower, Joe Allen, Nathan Dyer, Scott Sinclair (Cedric van der Gun, 73'), Stephen Dobbie (Frank Nouble, 68'). Subs: Yves Makabu-Makalambay (GK), Craig Beattie, Andrea Orlandi, Jordi Lopez.
Attendance: 11,485 Away: 599
Referee: Iain Williamson (Berkshire)
The Swans welcome back Scott Sinclair and Stephen Dobbie from injury. Both players missed out at Forest with hamstring and ankle problems respectively but return to the starting line-up at Brendan Rodgers' old club.
Darren Pratley misses out through the shoulder injury he picked up at the City Ground; Ashley Williams duly pushes up into midfield and Albert Serran slots in at the back.
The other absentee is David Cotterill (groin), but Angel Rangel and Craig Beattie also return from their lay-offs to make the substitutes' bench.
Four games on the road without a point had preceeded this fixture but a first return to Vicarage Road for Brendan Rodgers would have been a nice way to break that away day duck.
It's not as if the performances on the road had been poor but the Swans found themselves heading into October with nothing to show from their efforts at Hull, Norwich, Leeds and Nottingham Forest.
Watford was the venue for the Swans' last away success nearly seven months before this game, and the start on a chilly night in Hertfordshire this time around was a promising one.
The returning Stephen Dobbie almost conjured up an opening early on but the Scottish striker did play his part in the visitors taking an 11th minute lead.
He played the ball through on goal for another player returning from injury, top-scorer Scott Sinclair, and he made no mistake in lifting the ball over Scott Loach to score an incredible eight in nine appearances.
The Swans certainly hit the ground running and a fine touch from Alan Tate to bring down Joe Allen's crossfield pass almost wielded a second, knocking the ball past Andrew Taylor and launching the ball across goal, taking a touch along the way to guide it out for a corner.
But it simply got better as the game hit the half-hour as Dobbie turned goalscorer, latching on to Allen's through ball and superbly finishing past Loach from the edge of the box, with the aid of the underside of the bar.
Watford weren't down and out and threatened to pull it back inside the proceeding eight minutes - the first from Don Cowie's delivery from which Adrian Mariappa saw a header cleared off the line by Tate, while another Cowie delivery was cleared to Danny Graham whose drive was well saved by Dorus de Vries' legs.
This game continued to flourish in stoppage time with Sinclair racing onto the end of Mark Gower's through ball, rounding the 'keeper but winning his side a corner, while down at the other end de Vries made another excellent stop to deny Jordan Mutch.
Half-Time: Watford 0 Swans 2
Scott Sinclair was certainly a steal from Chelsea. He's already proved that he can do the business in front of goal while his pace is frightening full-backs in every game he plays.
By the start of the second period he could easily have already scored a hat-trick, while another burst of pace almost set-up a third - the 21-year-old stunned the Hornets defence as he embarked on a 60-yard run down the left and as he approached goal had Nathan Dyer to pick out unmarked in the centre.
Unfortunately it drifted behind the winger otherwise the visitors could have found themselves three goals to the good.
Sinclair went alone just after the hour and was inches away from scoring a third, Gower again doing the initial damage to send the pace man on his way but, from eight-yards, he pulled his shot beyond Loach but past the post.
Angel Rangel was introduced as a replacement for Neil Taylor to make his second appearance of the season, and hot on his heels was loanee striker Frank Nouble - and his first touch is one that he wouldn't forget in a hurry.
The big man was barely on the pitch for 60 seconds when he put the Swans into a comfortable position, touching home what looked like to be a wayward Nathan Dyer shot after he was put through again by Gower.
All 599 fans in the visiting end were bouncing as they then saw Danny Graham squander a great chance from close-range, but Watford did find a route back into the game as substitute Troy Deeney dinked past de Vries with 14 minutes left on the clock. The striker even came close to scoring again moments later but glanced Jordan Mutch's cross wide of goal.
But the Swans were guaranteed a nervy ending when Martin Taylor towered to head home Lloyd Doyley's cross five minutes from time following a long spell of pressure from the Hornets.
Watford even had the ball in the net deep into injury-time, for a moment the home fans thought their side had completed a memorable comeback, fortunately that strike was ruled out for offside and the Swans managed to hold out for the remaining seconds to clinch a first away win of the season.