Match ends, Birmingham City 2, Watford 1.
Clayton Donaldson scored twice to knock Watford off the top of the Championship as Gary Rowett maintained his unbeaten start as Birmingham boss.
Donaldson turned in Stephen Gleeson's pass with a deflected shot to put the home side ahead after 80 seconds.
Fernando Forestieri brought Watford level quickly, converting Lloyd Doyley's cross at the second attempt.
But Donaldson headed in a cross from David Cotterill to seal Birmingham's second win in 26 home league games.
Despite the victory, Birmingham remain in the Championship's bottom three because of Brighton's win over Wigan.
|Birmingham's home help|
|Since beating Millwall on 1 October 2013, Birmingham had won just one home league game before overcoming Watford - defeating Brighton 1-0 on 16 August|
They went ahead from their first attack as Gleeson, in space on the left, found Donaldson, who stretched to beat keeper Heurelho Gomes from 15 yards with the help of a deflection.
Watford equalised as Forestieri collected Doyley's ball and side-stepped a defender to beat Darren Randolph from eight yards after the keeper saved his first effort.
The dangerous Cotterill curled a shot wide from outside the area, then struck a free-kick that forced a good save from Gomes, who also pushed away a long-range Gleeson shot.
Randolph saved well from Odion Ighalo and Troy Deeney to keep the score level at the break.
There were fewer clear chances in the second half, with Gleeson volleying wide and Watford midfielder Daniel Tozser making an important block to deny David Davis.
But Donaldson won it with five minutes left when he nodded Cotterill's right-wing cross past Gomes to end Watford's nine-match unbeaten run.
Birmingham manager Gary Rowett: "I certainly think we shouldn't play with any fear here. You could see the pressure on one or two at some stage but I felt they overcame it very well.
"The crowd will get behind you but only if you give them something. They were ready to grab something and that performance will have encouraged them."
Watford head coach Slavisa Jokanovic: "I am disappointed because it wasn't a good result for us. We tried to take control of the game and we had possession of the ball but we played slowly.
"We made some changes because we had some injured people and Fernando didn't start the last game. It's not an excuse, I don't believe my team was tired."
- 26DavisBooked at 51mins
- 22ShinnieSubstituted forThomasat 79'minutes
- 24ArthurSubstituted forGrayat 74'minutes
- 11ForestieriSubstituted forVydraat 75'minutes
- 24IghaloSubstituted forAndrewsat 59'minutesBooked at 81mins
- 9DeeneyBooked at 89mins
- Mark Heywood
- Shots on Target
Second Half ends, Birmingham City 2, Watford 1.
Attempt saved. Stephen Gleeson (Birmingham City) right footed shot from outside the box is saved in the centre of the goal. Assisted by David Cotterill.
Foul by Joel Ekstrand (Watford).
Clayton Donaldson (Birmingham City) wins a free kick on the right wing.
Troy Deeney (Watford) is shown the yellow card for a bad foul.
Foul by Troy Deeney (Watford).
Michael Morrison (Birmingham City) wins a free kick in the defensive half.
Attempt saved. Ikechi Anya (Watford) left footed shot from the left side of the box is saved in the bottom left corner. Assisted by Matej Vydra.
Offside, Watford. Troy Deeney tries a through ball, but Ikechi Anya is caught offside.
Goal! Birmingham City 2, Watford 1. Clayton Donaldson (Birmingham City) header from very close range to the bottom left corner. Assisted by David Cotterill with a cross.
Foul by Troy Deeney (Watford).
Paul Caddis (Birmingham City) wins a free kick in the defensive half.
Attempt missed. David Cotterill (Birmingham City) right footed shot from long range on the right is too high from a direct free kick.
Keith Andrews (Watford) is shown the yellow card for a bad foul.
Foul by Keith Andrews (Watford).
Paul Caddis (Birmingham City) wins a free kick on the right wing.
Substitution, Birmingham City. Wes Thomas replaces Andrew Shinnie.
Lewis McGugan (Watford) wins a free kick in the defensive half.
Foul by David Davis (Birmingham City).