The 62-year-old, who has played for and managed both clubs, is backing the League Two outfit to claim their fourth Premier League scalp.
"It's a perfect fixture for me because I've been manager at both clubs and had good experiences. Both of the clubs have had an amazing journey - but I'll probably go for the minnows because the city needs something," The Sun quotes him as saying.
"We know what can happen in the cup. I played in a famous one for Leeds versus Sunderland in the 1973 FA Cup final. We were certainties but got beaten.
"If I was the manager of Bradford, I'd tell the players to enjoy it - in big games you can be shattered before you play because of nerves. If you can enjoy it then you will play well."
Bradford have already defeated Wigan Athletic, Arsenal and Aston Villa on their way to Wembley.