Alan Tate's injury-time header rescued a draw for Swansea at Liberty Stadium where Lee Trundle made his eagerly awaited return as a substitute.
Watford had striker Danny Graham and home goalkeeper Dorus de Vries to thank for their opening goal.
Striker Graham's 66th-minute free-kick went through de Vries' legs.
But Watford, inspired by keeper Scott Loach, were equal to the hosts' desperate attempts to level until Tate headed home from a disputed corner.
Trundle revels in hero's return
Loach parried Marcos Painter's close-range header away and a combined Trundle-Craig Beattie effort also failed as the Hornets' keeper held strong.
Trundle then sent a free header wide from six yards out only for Tate to show the signing from Bristol City how it should be done.
However, Swansea remain on one Championship win for the season while Watford have also won only once in the league.
Swansea boss Paulo Sousa:
Sousa hails 'special' signings
"The game turned out to be just as we expected, playing against a Watford side so good in midfield.
"It was very balanced in the first half but after they scored their goal we showed a good reaction, particularly as we had some tired players out there.
"The new players at the club brought a lift to the team and in the end we looked more like winning the match - but a draw was a fair result."
Watford manager Malky Mackay:
"We are very disappointed to lose two points so late in the game, but we have a very young squad of players who respect each other and they put on a good performance at a very tough place.
"There is no frustration at the club because we have lost so many players in the transfer window during the last week, but it was important for the club as a whole to ensure that we go forward in the best way possible.
"We are trying to bring players into the club as we realise we are very light on numbers."
90:00+5:09 The referee signals the end of the game.
90:00+4:47 Corner taken by Mark Gower from the left by-line played to the near post, save by Scott Loach.
90:00+3:57 Mark Gower takes the inswinging corner, Nathan Ellington manages to make a clearance.
90:00+2:19 Mark Gower provided the assist for the goal.
90:00+2:19 GOAL - Alan Tate:Swansea 1 - 1 Watford Alan Tate scores a headed goal from deep inside the penalty area. Swansea 1-1 Watford.
90:00+1:49 Jon Harley challenges Kerry Morgan unfairly and gives away a free kick. Mark Gower delivers the ball,
90:00+1:20 Corner taken by Mark Gower from the left by-line to the near post, Nathan Ellington manages to make a clearance.
89:54 Corner from the left by-line taken by Kerry Morgan, save made by Scott Loach.
88:49 Mark Gower produces a cross, Lee Trundle has a headed effort at goal from close in which goes wide left of the goal.
88:26 Booking Scott Loach goes into the book for time wasting.
84:34 Substitution Andrea Orlandi goes off and Besian Idrizaj comes on.
83:08 Lee Hodson fouled by Craig Beattie, the ref awards a free kick. Free kick taken by Jay DeMerit.
81:56 Shot by Andrea Orlandi. Save made by Scott Loach. Corner taken short by Mark Gower. Marcos Painter has an effort at goal from
outside the penalty box missing to the wide left of the goal.
80:24 Substitution (Watford) makes a substitution, with Will Hoskins coming on for Danny Graham.
79:39 Craig Beattie takes a shot. Save by Scott Loach. Corner taken right-footed by Mark Gower, Marcos Painter takes a shot. Blocked
by Jay DeMerit.
78:01 Jon Harley gives away a free kick for an unfair challenge on Andrea Orlandi. Andrea Orlandi restarts play with the free kick.
75:20 Substitution (Swansea) makes a substitution, with Kerry Morgan coming on for Nathan Dyer.
75:20 Substitution Don Cowie goes off and Jon Harley comes on.
73:01 Foul by Jay DeMerit on Nathan Dyer, free kick awarded. Jordi Lopez has an effort direct from the free kick. Jordi Lopez produces
a left-footed shot from the edge of the area and misses to the left of the goal.
71:20 Free kick awarded for a foul by Danny Graham on Alan Tate. Dorus De Vries takes the free kick.
69:47 Substitution Lee Trundle comes on in place of Leon Britton.
68:36 Scott Loach restarts play with the free kick.
68:36 Booking Andrea Orlandi goes into the book for unsporting behaviour.
68:32 Free kick awarded for a foul by Andrea Orlandi on Henri Lansbury.
67:09 Inswinging corner taken from the left by-line by Mark Gower, clearance made by Henri Lansbury.
65:13 Assist on the goal came from Tom Cleverley.
65:13 GOAL - Danny Graham:Swansea 0 - 1 Watford Danny Graham scores a goal from the edge of the penalty area to the top right corner of the goal. Swansea 0-1 Watford.
64:28 Tom Cleverley restarts play with the free kick.
64:28 Booking Booking for Ashley Williams for unsporting behaviour.
63:51 Unfair challenge on Nathan Ellington by Ashley Williams results in a free kick.
61:31 Free kick awarded for a foul by Andrea Orlandi on Henri Lansbury. Jay DeMerit restarts play with the free kick.
60:10 Direct free kick taken by Jay DeMerit.
60:10 Booking Marcos Painter receives a caution.
60:07 Foul by Marcos Painter on Danny Graham, free kick awarded.
54:01 Shot from 20 yards from Andrea Orlandi. Blocked by Jay DeMerit. Corner taken right-footed by Andrea Orlandi, Unfair challenge
on Scott Loach by Craig Beattie results in a free kick. Free kick taken by Scott Loach.
53:28 Foul by Nathan Ellington on Alan Tate, free kick awarded. Direct free kick taken by Alan Tate.
52:41 Substitution Nathan Ellington on for Marvin Sordell.
51:36 Matthew Collins crosses the ball, Craig Beattie takes a shot. Save made by Scott Loach.
Correction - 50:41 Free kick awarded for an unfair challenge on Andrea Orlandi by Henri Lansbury. Dorus De Vries takes the free kick.
50:41 Free kick awarded for an unfair challenge on Andrea Orlandi by Henri Lansbury. Dorus De Vries takes the direct free kick.
50:04 Matthew Collins challenges Danny Graham unfairly and gives away a free kick. Scott Loach takes the free kick.
46:43 Jordi Lopez takes a shot. Save by Scott Loach.
46:03 Corner taken by Tom Cleverley from the right by-line.
45:01 The match restarts for the second half.
45:00+1:08 The referee calls an end to the first half.
44:58 Andrea Orlandi fouled by Ross Jenkins, the ref awards a free kick. The free kick is delivered left-footed by Andrea Orlandi
from left channel, Adrian Mariappa manages to make a clearance.
43:22 The assistant referee signals for offside against Ross Jenkins. Free kick taken by Dorus De Vries.
43:01 Danny Graham takes a shot. Save made by Dorus De Vries.
42:13 Marcos Painter challenges Marvin Sordell unfairly and gives away a free kick. Tom Cleverley restarts play with the free kick.
38:54 Craig Beattie takes a shot. Save by Scott Loach.
38:13 Outswinging corner taken by Mark Gower, Ashley Williams takes a shot.
38:02 Shot by Alan Tate from 25 yards. Blocked by Ross Jenkins.
34:12 Leon Britton challenges Marvin Sordell unfairly and gives away a free kick. Tom Cleverley crosses the ball from the free kick
right-footed from right wing, save by Dorus De Vries.
32:29 Tom Cleverley delivers the ball, comfortable save by Dorus De Vries.
31:29 Short corner worked by Tom Cleverley.
29:33 Ross Jenkins challenges Nathan Dyer unfairly and gives away a free kick. Nathan Dyer takes the free kick.
27:20 Nathan Dyer challenges Adrian Mariappa unfairly and gives away a free kick. Scott Loach restarts play with the free kick.
25:22 Tom Cleverley takes a shot. Save made by Dorus De Vries.
24:20 Marvin Sordell produces a cross, Dorus De Vries makes a save.
21:30 Craig Beattie is ruled offside. Scott Loach restarts play with the free kick.
18:20 Danny Graham concedes a free kick for a foul on Craig Beattie. Andrea Orlandi takes the free kick.
17:42 Free kick awarded for a foul by Marvin Sordell on Alan Tate. Alan Tate restarts play with the free kick.
16:38 Mark Gower takes a shot.
15:07 Henri Lansbury delivers the ball, Dorus De Vries makes a save.
12:58 Outswinging corner taken from the left by-line by Andrea Orlandi, Close range header by Alan Tate goes wide of the left-hand
11:28 Mark Gower sends in a cross, Header from deep inside the area by Matthew Collins goes harmlessly over the crossbar.
6:28 Corner taken by Tom Cleverley, Adrian Mariappa has a header from close in and clears the crossbar.
5:16 Andrea Orlandi fouled by Henri Lansbury, the ref awards a free kick. The free kick is swung in right-footed by Mark Gower,
Dorus De Vries makes a comfortable save.
0:00 The game kicks-off.
Live text and data provided by The Press Association.
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