Town have recalled Tommy Smith from his loan spell at Brentford.
Roy Keane made contact with the Bees over the weekend following Damien Delaney's red card against Scunthorpe at the weekend and the New Zealand international is now back with Blues.
"We have brought back Tommy as cover and we've got Pim [Balkestein] as well so we are not too bad for numbers," Roy told the Club website.
"I was thinking about bringing Tommy back anyway. He's been training with us and you can see he's benefited from going to Brentford because he's been playing games.
"He's back with us today and he should be available for the Watford match."
Tommy, who was scheduled to stay with Brentford until April, made eight appearances in his time at Griffin Park.
Town have appealed over Damien's red card and that will be heard at 1.00pm on Tuesday.