Watford come into this fixture off the back of an emphatic victory against Rotherham United, beating the Millers 4-1 on Tuesday with Francisco Sierralta, Ismaïla Sarr, Ken Sema and Dan Gosling all on target. This result moved the Hornets into second place, with Xisco Muñoz's side winning each of their last four EFL Championship matches.
Lee Bowyer got off to a winning start as Birmingham boss the following day, beating promotion contenders Reading 2-1 with goals from Lukas Jutkiewicz and Harlee Dean. This result saw Blues move six points clear of the relegation zone, albeit with 22nd placed Rotherham United crucially holding four games in hand.
Former Birmingham goalkeeper Ben Foster is in line to replace Daniel Bachmann after two months out with a broken finger, as Dan Gosling pushes for a start after coming off the bench to score in Watford's win on Tuesday. Ismaïla Sarr also faces a late fitness test after sustaining a knock.
There are question marks over the fitness of Jérémie Bela and Iván Sánchez, as Jonathan Leko may be reinstated into the starting eleven after impressing in Wednesday's win.
Foster; Femenia, Troost-Ekong, Sierralta, Masina, Chalobah, Hughes, Zinckernagel, Sarr, Sema, Pedro.
Etheridge; Colin, Roberts, Dean, Pedersen, Halilović, Gardner, Harper, Leko, Hogan, Jutkiewicz.
Ones to watch
The Senegalese winger has already showcased on multiple occasions this season that he is a special player, with his ability to breeze past defenders, score goals as well as create them, recording nine goals and nine assists thus far. Sarr has featured heavily for Watford this season, playing in 33 EFL Championship games, and if Watford are to continue their sublime form at Vicarage Road this season, Sarr will play a huge part if fit.
The experienced Championship striker played a pivotal role in Wednesday's win, scoring the game's opening goal and combining well with Scott Hogan to cause Reading problems. Jutkiewicz has struggled to find form this season, scoring twice in 34 games prior to Lee Bowyer's arrival. Playing in a 4-4-2 system that is more suited to the striker, Jutkiewicz looks set to thrive under Bowyer's management and cause problems once more on Saturday.
When these sides met earlier in the season, Watford emerged 1-0 victors, with a late penalty from Birmingham fan Troy Deeney deciding the game.
Birmingham's last win against Watford came in a 2-1 victory at St Andrews, with Clayton Donaldson bagging a brace on the night.
How to watch
The game will be available to watch at 3pm on Saturday on Sky Sports Football.
In the build-up to the game, Watford head coach Xisco Muñoz said: 'Everyone is working hard in the training ground for our amazing challenge that we have.
''This is very important for us as we play with passion, we play with ambition and always when the fans look at our games, they feel the same. They feel this is my team. This is our team. These are our warriors.''
Birmingham City head coach, Lee Bowyer said:
'Watford are a Premier League side, they have pace, strength and are direct. They are a good team, but they have weaknesses. All sides have weaknesses. We need to take our chances and capitalise on those and work hard for each other."