Liverpool and Birmingham have met eight times in the FA Cup with the Reds winning five times. There have been two draws while City have triumphed just once - 2--0 at Anfield on January 10 1931.
The sides have clashed twice in modern times - firstly in 1995 when Liverpool needed a penalty shoot-out to overcome their opponents in a replay - and most recently in 2002 when a third round tie at Anfield was settled by a first half Michael Owen brace and a late Nicolas Anelka strike.
But while historically, Liverpool have the upper hand, current manager Benitez is yet to taste victory over Birmingham after four times of asking.
Liverpool failed to even find the net against Steve Bruce's side in Benitez's debut season - going down to a league double - 1-0 at home and 2-0 away.
Both of their 2005-06 Premier-ship tussles have ended all-square with a 2-2 draw at St Andrews back in September followed by a 1-1 result at Anfield at the start of last month.
The 10-man visitors earned an unlikely share of the spoils through an 88th-minute own goal by Xabi Alonso which cancelled out Steven Gerrard's opener to mar Robbie Fowler's homecoming.
Benitez said: "They're a very difficult team to play against physically and they work hard for 90 minutes.
"Last time, we were controlling the game and made a mis-take and conceded an own goal.
"They work really hard and I have seen the video of their last game against Spurs and they caused the opposition a lot of problems.
He added: "For me, the FA Cup is the same as last season in that it is very important.
"For Birmingham, I don't know their priorities.
"The league is more important because you could win this game and then the next but lose the final.
"In the end if Birmingham were relegated and lost the final it would be bad for the club.
"I don't want to change Steve Bruce's mind but they'll think of the league for sure."
Birmingham, who go into the tie still stranded in the relegation zone, down in 18th place in the Premiership, have got some serious selection worries.
Former Liverpool striker Emile Heskey is a major doubt to face his former club tonight while midfielder Nicky Butt is also struggling.
Heskey and Butt will have late fitness tests on ankle and hip injuries respectively suffered during Saturday's 2-0 home reversal against Tottenham.
David Dunn and Jiri Jarosik are also doubtful while Julian Gray, Matthew Upson, Muzzy Izzet, Chris Sutton and Mehdi Nafti are all sidelined.
Former Brentford striker DJ Campbell is cup-tied to leave just Mikael Forssell as possibly the only available striker if Heskey is ruled out.
