Deeney, making his 500th league appearance, had scored four times against Birmingham previously, but found it hard going on this occasion in a game of few chances.

There was little to choose between the teams in the first half but Watford noticeably stepped up the tempo after the break and had the better of the play to deserve their second successive win.

Birmingham, who have now gone five home games without a win, made five changes to the side that beat Reading 2-1 away on Wednesday night.

Josh Dacres-Cogley, Jake Clarke-Salter, Mikel San Jose, Gary Gardner and Lukas Jutkiewicz replaced Maxime Colin, Harlee Dean, Ivan Sanchez, Jon Toral and Scott Hogan.

Dean was suspended after being sent off at Reading, while the other four players were on the bench.

Watford made three changes from the team that beat Rotherham United 2-0 on Tuesday night.

Ben Wilmot, James Garner and Domingos Quina came in for Christian Kabasele, Stipe Perica and Ismaila Sarr.

In a first half hour littered with free kicks for fouls, there were no chances for either team until the 36th minute, only a booking for Birmingham midfielder Maikel Kieftenbeld for a late foul on Quina.

When the only chance of the first half came nine minutes before the break, Birmingham were a whisker from taking the lead.

San Jose got a foot to flick on Gardner's corner and the ball hit the far post before bouncing to safety.

On the stroke of 45 minutes, there was a long delay after a clash of heads between Watford midfielder Tom Cleverley and Birmingham striker Jutkiewicz, who came off worse and needed extensive treatment.

Jutkiewicz finally emerged with a bandage on the side of his head and was able to continue.

The second half continued in the same vein as much of the first – without incident for long periods.

Deeney's first big chance came in the 68th minute after Wilmot put him through to beat the offside trap, but he lobbed straight at Etheridge.

The striker then teed up James Garner but the midfielder's low volley from the edge of the box lacked the power to beat Etheridge.

Deeney had a more difficult chance to mark his milestone in the 77th minute but could only glance well wide from 12 yards when he connected with Ken Sema's cross.

The moment of glory for Deeney came five minutes from time when Pedersen brought down substitute Perica after he broke into the box.

Blues' only second-half effort on target came in the third minute of time added on when Gardner's 22-yard free kick was brilliantly fingertipped around the post by former Blues goalkeeper Ben Foster.