The recent defeats of Aston Villa and Ipswich, along with the hard-earned point at Bolton, have lifted Rovers out of the drop zone for the first time since February 9. Rovers currently occupy 15th in the table.
Souness is delighted with the current run, but is under no illusions over the magnitude of Sunday's task.
He said: "It is a very big game for both teams. Leeds still have a Champions' League place to play for and will be going all out.
"We have had a good run recently, but you get nothing for looking back. It will be difficult for us on Sunday, but then again, every game is difficult."