Troy Deeney's goal earned Watford an opening day win at Birmingham as they reacted in positive fashion to last season's play-off final defeat.
The striker finished clinically with his right foot from Fernando Forestieri's pass to give Gianfranco Zola's men the perfect season start.
Wade Elliott hit the bar for the hosts while Dan Burn had a shot saved by Hornets keeper Manuel Almunia.
Marco Cassetti almost doubled the Hornets' lead late on.
Watford missed out on promotion to the Premier League last season after losing the play-off final to Crystal Palace at Wembley.
But Zola vowed his side would be stronger for the experience and they were true to his word at St Andrew's with a battling victory.
Giving Birmingham the blues
Watford striker Troy Deeney's two visits to St Andrews in 2013 have yielded three goals
The decisive strike came on 11 minutes as Deeney played a one-two with Forestieri before racing into the box and slotting into the far bottom corner.
Blues debutant Matt Green could have levelled but, after squirming free of defenders Gabriele Angella and Lloyd Doyley, he missed the target with just Almunia to beat.
Lee Clark's side went even closer when Elliott's 25-yarder took a deflection and Almunia tipped the ball onto the crossbar.
With 10 minutes to go, and play swinging from end to end, an unmarked Kyle Bartley should have levelled but the defender's close-range header went wide.
Birmingham manager Lee Clark: "I've told the players that there is no need to change anything. On another day we would have got at least a draw.
"We didn't deserve to lose against a terrific team who will be there again at the end of the season because of the pace they play at.
"I believe we have hit the ground running and been unfortunate in terms of the result. We just didn't get that little bit of luck."
Watford manager Gianfranco Zola: "I am pleased with the win. It was a tough test to start the season. This is why I am pleased with result and the performance.
"In first half we were excellent for long spells. Perhaps we should have tried to have taken more chances and scored more than one goal.
"Birmingham came back stronger in the second half. We dropped a little bit physically and we allowed them to cause us a lot of problems."
Live Text Commentary
Corner taken by Scott Allan from the left by-line.85:29 Booking
Booking for Lee Novak.81:43
Troy Deeney makes a clearance.81:39
Corner taken by Wade Elliott from the right by-line.80:51 Substitution
Substitution Shane Ferguson goes off and Christopher Burke comes on.80:25
Header by Lee Novak misses right.79:50
Corner taken by Shane Ferguson.79:23
The ball is delivered by Shane Ferguson.74:21 Substitution
Substitution Daniel Pudil joins the action as a substitute, replacing Ikechi Anya.74:00 Substitution
Substitution Scott Allan replaces Matt Green.72:02
Marco Cassetti has an effort at goal. Darren Randolph fumbles the ball.71:02
Wade Elliott crosses the ball in from the free kick.70:14 Booking
Booking for Cristian Battocchio for unsporting behaviour.70:08
Cristian Battocchio challenges Paul Robinson unfairly and gives away a free kick.68:09 Substitution
Substitution Fernando Forestieri leaves the field to be replaced by Diego Fabbrini.67:57 Substitution
Substitution (Watford) makes a substitution, with Cristian Battocchio coming on for Lewis McGugan.67:21
Shot by Fernando Forestieri missed to the left of the target.66:36
Free kick taken by Manuel Almunia.
Lee Novak concedes a free kick for a foul on Fernando Forestieri.65:37
Dan Burn has an effort at goal. Manuel Almunia parries the effort to safety.65:25
Corner from the right by-line taken by Shane Ferguson.64:58
Wade Elliott takes a shot and strikes the bar.64:08
Shane Ferguson crosses the ball in from the free kick.62:32
Marco Cassetti gives away a free kick for an unfair challenge on Matt Green.62:00
The ball is sent over by Marco Cassetti.60:40
Clearance made by Paul Robinson.60:32
Marco Cassetti crosses the ball in from the free kick.59:54
Kyle Bartley concedes a free kick for a foul on Fernando Forestieri.58:48
Wade Elliott takes the free kick.58:35
Santos Iriney concedes a free kick for a foul on Andrew Shinnie.57:17
Almen Abdi takes the free kick.55:44
Unfair challenge on Lewis McGugan by Kyle Bartley results in a free kick.52:30
Wade Elliott takes a shot. Blocked by Lloyd Doyley.52:08
Free kick taken by Lewis McGugan.51:53
Free kick awarded for an unfair challenge on Lewis McGugan by Wade Elliott.50:47
Clearance by Santos Iriney.50:41
Free kick taken by Shane Ferguson.50:19
Unfair challenge on Matt Green by Gabriele Angella results in a free kick.50:00
Ikechi Anya takes the chance to get an effort at goal. A parry by Darren Randolph prevents the goal.48:19
Free kick taken by Manuel Almunia.48:01
The referee blows for offside against Matt Green.47:46
Free kick taken by Darren Randolph.47:35
The referee blows for offside against Troy Deeney.47:18
Manuel Almunia takes the free kick.46:48
The official flags Matt Green offside.45:45
The ball is crossed by Matt Green.45:00 +5:25 Half time
Half Time The first half comes to an end.45:00 +2:30
Lloyd Doyley has an effort at goal. Darren Randolph catches the ball.45:00 +0:57
Corner from the right by-line taken by Lloyd Doyley.45:00 +0:27
Lewis McGugan has an effort direct from the free kick. Darren Randolph parries the effort to safety.44:25
Paul Robinson goes into the book for unsporting behaviour.44:25 Booking
Free kick awarded for an unfair challenge on Almen Abdi by Paul Robinson.43:40
Manuel Almunia takes the free kick.43:34
Lee Novak is ruled offside.43:05
Free kick taken by Wade Elliott.42:52
Handball decision goes against Lewis McGugan.41:31
Free kick taken by Almen Abdi.40:51
Lee Novak concedes a free kick for a foul on Fernando Forestieri.39:59
Wade Elliott takes the free kick.39:48
Santos Iriney concedes a free kick for a foul on Tom Adeyemi.39:20
Marco Cassetti restarts play with the free kick.38:24
Tom Adeyemi receives a caution for unsporting behaviour.38:24 Booking
Foul by Tom Adeyemi on Lewis McGugan, free kick awarded.37:13
The ball is delivered by Paul Robinson.35:51
Dan Burn is cautioned.35:51 Booking
Dan Burn concedes a free kick for a foul on Lloyd Doyley.35:19
Gabriele Angella makes a clearance.35:09
Corner from the right by-line taken by Wade Elliott.34:28
Shot by Lewis McGugan. A parry by Darren Randolph prevents the goal.33:36
Santos Iriney takes the free kick.33:28
Free kick awarded for a foul by Matt Green on Marco Cassetti.31:57
Clearance by Gabriele Angella.31:47
Corner taken by Wade Elliott.30:04
Matt Green takes a shot and went wide of the right hand upright.28:39
Header at goal by Lewis McGugan to the left of the net.28:09
Shane Ferguson makes a clearance.28:00
Corner taken by Almen Abdi.27:42
Clearance made by Shane Ferguson.27:37
Lewis McGugan sends in a cross.26:25
Marco Cassetti concedes a free kick for a foul on Wade Elliott.24:28
Free kick taken by Manuel Almunia.24:17
The referee blows for offside against Matt Green.23:56
Shane Ferguson takes the free kick.23:25
Fernando Forestieri concedes a free kick for a foul on Neal Eardley.23:12
Gabriele Angella makes a clearance.23:08
Corner taken by Shane Ferguson from the left by-line.22:53
Centre by Matt Green.20:14
Fernando Forestieri takes a shot and went wide left of the target.18:52
Corner from the right by-line taken by Almen Abdi.17:46
Darren Randolph restarts play with the free kick.17:14
Corner taken by Almen Abdi from the left by-line.14:35
Lloyd Doyley gives away a free kick for an unfair challenge on Lee Novak.13:25
Darren Randolph makes a clearance.13:18
Corner taken by Lloyd Doyley.10:30
The assist for the goal came from Fernando Forestieri.10:30 Goal scored
Goal! - Troy Deeney - Birmingham 0 - 1 Watford Troy Deeney grabs a goal with a right foot finish. Birmingham 0-1 Watford.9:09
Clearance by Marco Cassetti.9:03
Centre by Shane Ferguson.7:56
The ball is delivered by Lee Novak.6:58
Gabriele Angella makes a clearance.6:47
Corner taken by Shane Ferguson from the left by-line.6:29
Lewis McGugan manages to make a clearance.6:22
Corner taken by Shane Ferguson.4:40
Dan Burn manages to make a clearance.4:34
The ball is crossed by Ikechi Anya.2:51
Free kick taken by Manuel Almunia.2:37
Matt Green gives away a free kick for an unfair challenge on Marco Cassetti.1:14
Free kick taken by Dan Burn.1:03
The referee blows for offside against Fernando Forestieri.0:00
The referee gets the game started.
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