The Spurs right-back was born and raised in Sheffield and, along with the rest of his family, he is a big fan of the Blades.
The 24-year-old makes no secret of his Yorkshire roots and his love for the Blades, even going to Wembley last season to watch their FA Cup semi-final against Hull, but he is determined to reach the final at their expense.
“It’s such an important game, especially for me,” Walker said.
“It’s not going to be easy. Hopefully we can get a comfortable lead here because this is our patch, but we need to play the football we have been playing in recent weeks.
“It is going to be a far from easy tie, especially up at Bramall Lane. They will chuck everything at us up there.
“I have obviously supported the club since I was a boy and played for the club before I came here.
“I know their spirit and what the coaches will want. It’s going to take a lot of hard work for us to get to Wembley.”
This will be just the second time Walker has played against United, having featured at Bramall Lane in an FA Cup third-round tie when on loan at Aston Villa four years ago.
“I played my first game on loan for Aston Villa against United in the cup and scored,” he said. “Not only that but it was with my left foot.
“I think as a professional footballer you have to do your job. My heart will always be with Sheffield United but I am a Tottenham player and they are my club.”
There are no such split loyalties for Walker’s family, though.
“No (they won’t be cheering me on) – they are Sheffield United fans,” he said.
“They obviously support me and want me to do well, but they will be wanting Sheffield United to go through, although it is a bit of a win-win situation for them because either way they will go to Wembley.”