The Welshman who played nearly 500 games in total for both clubs died in 2011 at the age of 42.
Speed had shirt number 11 at Newcastle and in his memory, fans from both clubs are planning to sing his name in the 11th minute of tonight's encounter.
Around 7,000 Leeds United fans are heading up the A19 to cheer on Brian McDermott's men at St James' Park.
Speaking after the draw was made last month, McDermott said: "The first thing that struck me about it was Gary Speed. He was a great man who played for both clubs and it’ll be a special occasion."
The Magpies have reportedly sold 26,000 tickets, and cash turnstiles will be in operation on the night.